U2OS cells were transfected with 0.025 µM control , S7 (S7#1), or L11 siRNA. Six hours before harvesting, cells were treated with ActD (5 nM), 5-FU (50 µM), doxorubicin (DOX, 0.03 µM) and daunorubicin (Dauno, 0.22 µM) (A) or hydroxyurea (HU, 1.5 mM) and deferoxamine mesylate (DFX, 250 µM) (B). Neocarzinostatin (NCS, 640 ng/ml) was added 2 hours before harvesting (A). Forty-eight hours after transfection, cell lysates were subjected to IB with indicated antibodies.