Aim To investigate the effects of Kruppel-like factor 4(KLF4) overexpression on the expression of heat shock protein25(HSP25). Methods Two stable cell lines were made by transforming pcDNA3.1/Myc-His(-) or pcDNA3.1/Myc-His-KLF4 into C₂C₁₂ cell.Reverse transcription polymerase chain reaction(RT-PCR) and Western Blot were employed to study the influence of KLF4 on the expression of HSP25 mRNA and protein respectively under normal physiological and heat shock conditions. Results Under normal physiological condition,the expression of HSP25 mRNA and protein in these two cell lines are relatively low.However,HSP25 mRNA level in KLF4 over expressed cell was significantly higher than that of empty vector cell lines not only under normal conditions but when recovered one hour and three hours after heat shock. Six hours after heat shock,the levels of HSP25 mRNA showed no significant difference between these two cell lines.Under both normal physiological conditions and different time intervals during the recovery of heat shock,the HSP25 protein level was higher in KLF4 over expressed cell line than that in the vector line. Conclusions Under both physiological and heat shock conditions,KLF4 over expression can enhance the expression of HSP25 in the myogenic C₂C₁₂ cell.