Selective processing of effector caspases in Lptn-induced apoptosis.

(A) Total proteins of CD4⁺ T cells activated for days 0.5 to 4 with the indicated stimuli were separated by SDS-PAGE and analyzed by Western blotting for detection of expression of caspases-4 and -7, and the PI3K control, using the antibodies described in “Materials and methods.” Arrows indicate the full-length forms of the caspases. Positive controls of expression of procaspase-7 (no variation with or without Lptn) and procaspase-4 (around 3-fold reduction with Lptn) are shown on CD3 and CD28 costimulation, as a representative experiment of 2. (B) Kinetics of procaspase-7 processing induced by Lptn. The graph represents the relative levels of the caspase-7/PI3K signal ratio induced by the indicated stimuli, with error bars corresponding to SD. These mean levels are representative of 2, 3, 5, and 2 independent experiments at 0.5, 1, 2, and 3 days, respectively. ▪, CD3; ▴, CD3 plus Lptn.