TNF-α/CHX- and CPT-mediated signaling in IEC-6 and ARPE-19 cells. IEC-6 and ARPE-19 cells were grown to confluence for 3 days, serum starved for 24 hours, and treated with a combination of TNF-α/CHX or CPT for 4 hours. (A) Cell lysates were separated on SDS-PAGE, and Western blot analysis was carried out using antibodies specific for phospho- and total- p53, Mdm2, p21Cip1, Bax, Bcl-2, Bcl-xL, and active caspase-3. Actin was used as loading control. (B) Cell lysates from this experiment were analyzed for the levels of phospho- and total- JNK1/2, Akt, and ERK1/2 by Western blot analysis.