Biochemical assays of proteins extracted from cryostat tissue sections.

(A) Western blotting using a 5.5% acrylamide gel. Anti-ALK (ALKc) detects a 250 kd band in lysates from the ALCL case expressing the CLCTL-ALK transcripts. This ALK protein is of a higher molecular weight than the normal 200 kd ALK protein present in the Rh30 cell line and the oncogenic 80 kd NPM-ALK expressed by the SU-DHL-1 cells. No ALK proteins were detected in tonsil lysates used as negative controls. (B) In vitro kinase assay using a 7.5% acrylamide gel. A phosphorylated 250 kd protein is present in the CLTCL-ALK-positive ALCL case. The 80 kd NPM-ALK protein expressed by SU-DHL-1 cells is used as a positive control. No corresponding bands were present in tonsil lysates.