(A) Diagram of the CS pathway. Pathway activation after IR is restrained by Chk1. Combined delivery of IR and Chk1 inhibitor (Gö6976) or siRNA activates the pathway. IR and Chk1 inhibition are individually insufficient for pathway activation (Sidi et al., 2008).
(B-E) HeLa cells transfected with the indicated siRNAs were treated with Gö6976 (1 μM) with or without IR (10 Gy) and harvested 24 hr post IR. Lysates were analyzed by western blot. pro-C2, procaspase-2; cl-C2 (p19), cleaved caspase-2, p19 fragment (mature cleavage product). cl-C2 images are longer exposures of the same membrane.
(F) HeLa cells stably expressing the indicated shRNAs were transfected with CHK1 siRNA (+) or LACZ siRNA (-), treated with or without IR (10 Gy) 16 hr after transfection, and harvested 16 hr post IR. Lysates were analyzed by western blot.
(G) HeLa cells transfected with the indicated siRNAs were treated with Gö6976 (1 μM) with or without IR (10 Gy) and harvested 24 hr post IR. Lysates were analyzed by western blot. C8, caspase-8; C9, caspase-9.
(H) HeLa cells stably expressing the indicated shRNAs and transfected with the indicated siRNAs were treated with Gö6976 (1 μM) with or without IR (10 Gy), and harvested 24 hr post IR. Lysates were analyzed by western blot. C3, caspase-3; C6, caspase-6; C7, caspase-7.
(I) SV40-transformed MEFs of indicated genotypes were treated with Gö6976 (1 μM) with or without IR (10 Gy) and harvested 24 hr post IR. Lysates were analyzed by western blot.