Immunoblot analysis of CPP32 in lymphoid cell lines. (A) Cell lysates were prepared, normalized for total protein content (50 μg per lane), and subjected to SDS-PAGE/immunoblot assay using 0.1% (vol/vol) anti-CPP32 antiserum, followed by HRPase conjugated goat antirabbit secondary antibody and an ECL substrate.47 The position of the unprocessed 32-kD CPP32 protein is indicated. Reprobing the blot with an antibody against tubulin confirmed loading of essentially equivalent amount of total protein for all samples (not shown). (B) Recombinant CPP32 was treated (+) or not treated (−) with granzyme B and subjected to SDS-PAGE immunoblot analysis. The positions of the 32-kD pro-enzyme and 17-kD subunit of the processed CPP32 protease are indicated.