PathScan^® Total ALK Sandwich ELISA Kit

CST's PathScan^® Total ALK Sandwich ELISA Kit #7322 detects endogenous levels of total ALK and NPM-ALK fusion proteins. High levels of phospho-ALK (Tyr1604) protein and phospho-NPM-ALK fusion protein are detected in Karpas299 cells where ALK and NPM-ALK are constitutively phosphorylated (Figure 1). These high levels are abolished in Karpas299 cells lysed without addition of phosphatase inhibitors* to the lysis buffer. The levels of total ALK protein (phospho and nonphospho) detected by PathScan^® Total ALK Sandwich ELISA Kit #7322 remain unchanged (Figure 1). Western analysis of protein captured in microwells coated with ALK antibody shows two bands corresponding to both ALK protein and NPM-ALK fusion protein (Figure 3). This kit detects proteins from the indicated species, as determined through in-house testing, but may also detect homologous proteins from other species.

* Phosphatase inhibitors include sodium pyrophosphate, β-glycerophosphate and Na₃VO₄.

Anaplastic lymphoma kinase (ALK) is a tyrosine kinase receptor for pleiotrophin (PTN), a growth factor involved in embryonic brain development (1-3). In ALK-expressing cells, PTN induces phosphorylation of both ALK and the downstream effectors IRS-1, Shc, PLCγ, and PI3 kinase (1). ALK was originally discovered as a nucleophosmin (NPM)-ALK fusion protein produced by a translocation (4). Investigators have found that the NPM-ALK fusion protein is a constitutively active, oncogenic tyrosine kinase associated with anaplastic lymphoma (4). Research literature suggests that activation of PLCγ by NPM-ALK may be a crucial step for its mitogenic activity and involved in the pathogenesis of anaplastic lymphomas (5).A distinct ALK oncogenic fusion protein involving ALK and echinoderm microtubule-associated protein like 4 (EML4) has been described in the research literature from a non-small cell lung cancer (NSCLC) cell line, with corresponding fusion transcripts present in some cases of lung adenocarcinoma. The short, amino-terminal region of the microtubule-associated protein EML4 is fused to the kinase domain of ALK (6-8).