Figure 4

Biochemical assays of proteins extracted from cryostat tissue sections and cytocentrifuge preparations. A, Western blotting of proteins extracted from sections of the anaplastic large cell lymphoma (ALCL) case using anti-ALK (ALKc) demonstrated the presence of a 125 kd protein (MSN-ALK) in the tumor cells. This was in contrast to the 80 kd NPM-ALK protein detected in the t(2;5)-positive SU-DHL-1 cell line. No ALK proteins were detected in normal tonsil lysates used as a negative control. B, An in vitro kinase assay of proteins immunoprecipitated with anti-ALK from the ALCL tumor demonstrated the presence of a 125 kd phosphorylated protein. A weaker band of comparable size was also observed in proteins immunoprecipitated by antiphosphotyrosine. In the ALK immunoprecipitates from the SU-DHL-1 cell line, the only band seen represents the 80 kd NPM-ALK.