UVB induces caspase activation and processing in IDC.

IDCs were exposed to 1 J/cm² UVB, and the activation and processing of caspase 8 (A), caspase 9 (B), and caspase 3 (C) was analyzed at the indicated time points by Western blot analysis. P43 and p45, derived from processing of both caspase 8 isoforms, as well as the p18 subunit, are indicated by arrows. Similarly, p18 and p17 subunits derived from caspase 9 and caspase 3 proteolytic processing, respectively, are indicated by arrows. (D) Caspase activation in cell lysates was functionally analyzed by the cleavage of in vitro–translated PARP. [S³⁵]-PARP was incubated with cell lysates from untreated IDCs or IDCs exposed to 1 J/cm²UVB and incubated at 5% CO₂, 37°C for 4 hours. Arrows indicate the 85-kd and 25-kd PARP cleavage products.