HSP70 affects cisplatin-induced MAPK signaling pathway activation. (A) HGC-27 cells were treated with cisplatin (5 µg/ml) for different amounts of time and the phosphorylation and total protein levels of (A) p38, ERK and JNK, and (B) Src, Akt and IκB, were monitored by western blotting. (C) HSP70-overexpressing and control plasmids were transfected into HGC-27 cells. (D) HGC-27 cells were pretreated with PES for 2 h and then stimulated with cisplatin for 6 or 8 h. (E) HSP70-shRNA and control plasmids were transfected into HGC-27 cells. After transfection, the cells were treated with cisplatin for 6 or 8 h and the phosphorylation and total protein levels of p38, ERK and JNK were monitored by western blotting. *P<0.05 compared with control cells at 6 h; #P<0.05 compared with control cells at 8 h. HSP70, heat shock protein 70; ERK, extracellular signal-regulated kinase; JNK, c-Jun N-terminal kinase; Src, SRC proto-oncogene non-receptor tyrosine kinase; Akt, AKT serine/threonine kinase 1; IκB, inhibitor of κB; sh, short hairpin; DDP, cisplatin; CON, control; p-, phosphorylated; PES, pifithrin-µ.