Effects of SAHA and cladribine on apoptotic regulatory proteins and signalling pathways. (A) Western blot analysis was performed for the indicated apoptotic regulatory proteins after treatment with SAHA (1, 2 and 5 µM), cladribine (0.125, 0.25 and 0.5 µM) or both for 24 h. Upper panels show representative Western blots, and the bar graph indicates average relative protein expression determined by densitometric analysis of three independent experiments. *P < 0.05, **P < 0.005, ***P < 0.0005 vs. C+S. S: SAHA, C: cladribine and C+S: cladribine + SAHA. (B) Apoptosis induction was detected by Western blot analysis of caspase-3 and PARP cleavage after treatment as described in (A). Results are representative of three independent experiments. (C) Western blot analysis was performed for phosphorylated (p)-ERK, total ERK, p-STAT3 and total STAT3 after treatment as described in (A). Results are representative of three independent experiments. Equal loading of protein lysates was confirmed by re-probing membranes for GAPDH.