Objective:To explore the role and mechanism of P311 in the differentiation of mouse skin fibroblasts (Fbs) into myofibroblasts.Methods:The study was an experimental research. Six 2-day-old male C57BL/6 mouse were used to extract skin Fbs by enzymatic hydrolysis method and routinely cultured. The 1 st to 3 rd passage cells were taken and divided into empty vector group transfected with empty adenovirus and P311 group transfected with P311 high expression adenovirus, and P311+myocardin-related transcription factor A (MRTF-A) small interfering RNA (siMRTF-A) group transfected with P311 high expression adenovirus and siMRTF-A according to the random number table. After 72 h of culture, the cell proliferation vitality of cells in 3 groups was detected by cell counting kit 8, the protein expressions of MRTF-A, α-smooth muscle actin (α-SMA), and serum response factor (SRF) in cells in 3 groups were detected by Western blotting, the collagen gel contraction assay was performed and the 72 h gel contraction rates in 3 groups were calculated. The sample numbers in the above experiments were all 3. The protein expressions of MRTF-A and SRF in cells, cytoplasm, and nucleus in cells in empty vector group and P311 group were detected by Western blotting, with sample number of 4. Results:After 72 h of culture, the cell proliferation vitality of cells in empty vector group, P311 group, and P311+siMRTF-A group was similar ( P>0.05). After 72 h of culture, compared with those in empty vector group, the protein expressions of MRTF-A, α-SMA, and SRF in cells in P311 group were significantly increased ( P<0.05), while the protein expressions of MRTF-A and SRF in cells in P311+siMRTF-A group were significantly decreased ( P<0.05). Compared with those in P311 group, the protein expressions of MRTF-A, SRF, and α-SMA in cells in P311+siMRTF-A group were significantly decreased ( P<0.05). The 72 h gel contraction rate showing cell contractility in P311 group was (84.8±6.2)%, which was significantly higher than (27.8±2.6)% in empty vector group and (24.7±3.2)% in P311+siMRTF-A group (with P values all <0.05). The 72 h gel contraction rates in empty vector group and P311+siMRTF-A group were similar ( P>0.05). After 72 hours of culture, the protein expressions of MRTF-A (with t values of 5.86 and 3.77, respectively, P<0.05) and SRF (with t values of 3.95 and 3.97, respectively, P<0.05) in cells and cytoplasm in P311 group were significantly higher than those in empty vector group, while the protein expressions of MRTF-A and SRF in the nucleus of cells were similar between the two groups ( P>0.05). Conclusions:P311 can promote the differentiation of fibroblasts into myofibroblasts through MRTF-A, and then participate in scar formation.