Figure 1.

Proteolytic cleavage of Cas during etoposide-induced apoptosis in Rat-1 cells. Rat-1 cells were exposed to 40 μM etoposide for the indicated periods. Cell lysates were then subjected to immunoblot analysis using Cas mAb (A) and Cas-2 (B). Intact Cas migrates at a molecular mass of 130-kDa. Cleavage products of Cas are shown (large arrowheads on the right; 31 and 47 kDa). The blot was then reprobed with FAK mAb (C), after which, to verify equal loading of protein, the blot was stripped once again and reprobed with tubulin mAb (D). Molecular mass standards are indicated by the small arrowheads on the left.