Hear shock protein 70(HSP70)is associated with apoptosis in cancer cells.However,the role of HSP70 in the regulation of c-Jun N-terminal kinase(JNK)-and p38 mitogen-activated protein kinase(p38 MAPK)-dependent growth and apoptosis in lung cancer cells remains largely unknown.In this study,we determined the effect of HSP70 by treatment with mild heat and JNK/p38 MAPK inhibitors on cell proliferation and apoptosis and explored the underlying mechanisms in A549 cells.We found that treatment of the cells with mild heat and JNK/p38 MAPK pathway inhibitors(SP600125 and SB203580)promoted cell proliferation in the presence of actinomycin D in A549 cells.We also showed that treatment with mild heat or SP600125 and SB203580 significantly slowed the steps of apoptosis induced by actinomycin D in A549 cells.Moreover,we found that HSP70 overexpression induced by mild heat markedly decreased the expression of cell growth and apoptosis-related protein p-JNK,p38 and caspase-3.By contrast,knockdown of HSP70 by siRNA HSPAIA-2009 effectively promoted the expression of the JNK and p38 MAPK.Taken together,our results indicate that HSP70 plays an important role in lung cancer growth and apoptosis through the activation of JNK and p38 MAPK signaling in actinomycin-D-treated lung cancer A549 cells