Tumor

GAPDH is a 146kD tetramer glycolytic pathway metabolic enzyme composed of four 30-40 kDa subunits. It is responsible for reversibly phosphorylating its substrate glyceraldehyde 3-phosphate within the glycolytic pathway.  Apart from its role in glycolysis, GAPDH may have other roles such as transcriptional activation. Due to its housekeeping role, GAPDH is highly expressed in almost all tissues, allowing its use as an internal loading control (traditionally for mRNA expression comparisons, but also in protein studies.

MMP24 is an extracellular matrix (ECM) degradative peptidase enzyme that is a member of the large family of matrix metalloproteinases (MMP). Each MMP has a different substrate specificity, and the aberrant or derailed expression of these is strongly correlated with unregulated events such as tumor invasion, metastasis, angiogenesis, and arthritis. This is in contrast to the tightly controlled normal physiological processes such as tissue remodeling, reproduction, rebuilding, and embryonic development. Deregulation often occurs through the loss of negative checks.

GPNMB is a type I transmembrane glycoprotein with homology to the PMEL17 precursor, a melanocyte-specific protein. Two transcript variants encoding different isoforms exist.GPNMB is expressed in minimally (but not highly) metastatic human melanoma cell lines and xenografts and may be involved in the delay and reduction of metastatic potential and growth.

Factor VII (coagulation factor VII) is a 50 kD multidomain single chain plasma glycoprotein synthesized in the liver. It is a vitamin K-dependent serine protease essential for the extrinsic pathway of hemostasis, or blood coagulation. Factor VII circulates in the blood in a zymogen form that is converted to an active form (via factor IXa, factor Xa, factor XIIa, or thrombin).

TNF alpha is a multifunctional proinflammatory cytokine that belongs to the tumor necrosis factor (TNF)-receptor superfamily. It is involved in the regulation of a wide spectrum of biological processes: cell proliferation, differentiation, apoptosis, inflammation, lipid metabolism, and coagulation. TNF alpha has been implicated in a variety of autoimmune diseases (rheumatoid arthritis, Crohn's disease, multiple sclerosis, and psoriasis), insulin resistance, septic shock, and tumor metastases related to cancer.

Keratins, also called cytokeratins, are a family of filamentous structural proteins that form the intermediate filaments within epithelial cells. Keratins are differentially expressed depending on both the epithelial cell origin and degree of differentiation. An antibody to any given keratin is useful either as a stand-alone or part of an antibody panel to help identify or clarify tissue origin. Cytokeratin 18 (CK18) is a 45 kD normal constituent of the hepatocyte cytoskeleton and is expressed in combination with cytokeratin 8.

Podoplanin is a mucin-type 1 transmembrane glycoprotein found in a wide range of tissues. It appears to be differentially expressed in endothelial cells of lymphatic but not blood vessel origin. In normal skin and kidney, podoplanin co-localizes with VEGFR3/FLT4, another marker for lymphatic endothelial cells. It appears to be involved in lymphangioigenesis and cell migration and is regulated by the lymphatic-specific homeobox gene Prox1. Podoplanin has also been found to be expressed on a wide variety of tumors.

Mucus is the viscous secretion that covers epithelial surfaces (trachea, colon, and cervix) and consists of twenty highly glycosylated proteins called mucins. The mucin family all are high-molecular weight proteins with oligosaccharides attached to the serine or threonine residues of their core protein backbone by O-glycosidic linkages. Mucins play fundamental roles in mucosal cell protection, lubrication, and communication with their external environment as detailed by Corfield¹. They have been implicated in epithelial renewal and differentiation.

The PIM-1 (proto-oncogene serine/threonine-protein kinase) protein is an epithelial-derived, integral membrane serine protease. This protease forms a complex with the Kunitz-type serine protease inhibitor, HAI-1, and is activated by sphingosine 1-phosphate. PIM-1 cleaves and activates hepatocyte growth factor/scattering factor (HGF) as well as urokinase plasminogen activator (uPA). Such downstream targets implicate this serine protease as an epithelial membrane trigger for a sequential protease cascade.

Nitric oxide (NO) is an inorganic, gaseous, and reactive free radical that acts as a biologic mediator in processes such as neurotransmission, vasorelaxation, and cytotoxicity. In addition, it has antimicrobial and anti-tumoral activities. NO production is mediated by members of the nitric oxide synthase (NOS) family. The NOS enzyme catalyzes the oxidization of L-arginine into L-citrulline and NO.  Several subtypes have been identified: two constitutive isoforms (type I brain/neuronal NOS, and type III endothelial) and one inducible isoform (iNOS, or type II).