Abstract: Objective To study the effect of macrophage stimulating protein (MSP) on the cell cycle of non-small cell lung cancer PC14 cells without expression of recepteur d’originenanta (RON) and MSP, and analyse its effect on PC14’s epithelial mesenchymal transition (EMT) capacity. MethodsVitro culture PC14 (blank control), PC14-Mst1-pEGFP-N1 (stablely expressed MSP) and PC14-pEGFP-N1. Cell cycles were detected by flow cytometry and the gaps between cells during growth were measured by transmission electron microscope (TEM); RT-PCR and Western blot were used to figure out the shifts of EMT related gene expression in PC14-Mst1-pEGFP-N1 cells. ResultsCompared with the PC14 group and PC14-pEGFP-N1 group, PC14-Mst1-pEGFP-N1 population of G1/G0 phase were significantly increased while S and G2/M phase were significantly reduced;The gaps between PC14-Mst1-pEGFP-N1 cells decreased; RT-PCR and Western blot showed that mRNA and protein levels of E-cadherin of PC14-Mst1-pEGFP-N1 were significantly higher than that of PC14, but mRNA and protein levels of Vimentin were significantly lower. ConclusionMSP may affect the cell cycle of PC14 and inhibit its EMT procedure by regulating the expression of related proteins including E-cadherin and Vimentin when RON was not expressed.