ObjectiveTo investigate the role of protease-activated receptor-2 (PAR-2) activation on the expression of vascular endothelial growth factor (VEGF) in MKN28 gastric cancer cells. Methods①MKN28 cells were treated with increased concentrations of trypsin (0, 0.1, 1.0, 10.0, and 100.0 nmol/L respectively) for 6 hours, or treated with 10.0 nmol/L trypsin for 3, 6, 12, and 24 hours (blank control group was treated with PBS) respectively, then the expression levels of VEGF mRNA and its protein in MKN28 cells were detected by real-time reverse transcription polymerase chain reaction (qRT-PCR) and Western bolt method, with the concentration of VEGF protein in broth was detected by enzyme linked immunosorbent assay (ELISA) method.②MKN28 cells were divided into blank control group (treated with PBS), trypsin group, trypsin+PD98059 group, trypsin+SB203580 group, PD98059 group, and SB203580 group, then the expression levels of VEGF mRNA and its protein in MKN28 cells were detected by qRT-PCR method and Western bolt method respectively. Results①The effect of different concentration of trypsin. Compared with blank control group, the expression levels of VEGF mRNA and its protein in 0.1, 1.0, 10.0, and 100.0 nmol/L group were higher (P < 0.05); compared with 0.1 nmol/L group, the expression levels of VEGF mRNA and its protein in 1.0, 10.0, and 100.0 nmol/L group were higher (P < 0.05); compared with 1.0 nmol/L group, the expression levels of VEGF mRNA and its protein in 10.0 and 100.0 nmol/L group were higher (P < 0.05); but there was no significant difference between 10.0 nmol/L and 100.0 nmol/L group (P > 0.05). The broth concentration of VEGF protein in blank control group, 0.1, 1.0, 10.0, and 100.0 nmol/L group crept upward (P < 0.05).②The effect of different treated time of 10.0 nmol/L trypsin. The expression levels of VEGF mRNA in blank control group, 3, 6, 12, and 24 hours group crept upward, and there was significant difference between any 2 groups (P < 0.05). But the expression of VEGF protein was not similar with VEGF mRNA. Compared with blank control group, the expression levels of VEGF protein in 3, 6, 12, and 24 hours group were higher (P < 0.05); compared with 3 hours group, the expression levels of VEGF protein in 6, 12, and 24 hours group were higher (P < 0.05); but there was no significant difference among 6, 12, and 24 hours group (P > 0.05). The broth concentration of VEGF protein in blank control group, 3, 6, 12, and 24 hours group crept upward, and there was significant difference between any 2 groups (P < 0.05).③The effect of extracellular regulated protein kinase (ERK) inhibitor (PD98059) and p38 inhibitor (SB203580). The expression levels of VEGF mRNA and its protein in trypsin group were all higher than corresponding indexes of blank control group, trypsin+PD98059 group, trypsin+SB203580 group, PD98059 group, and SB203580 group (P < 0.01), but there was no significant difference among blank control group, trypsin+PD98059 group, trypsin+SB203580 group, PD98059 group, and SB203580 group (P > 0.05). ConclusionActivation of PAR-2 can induce the expressions of VEGF mRNA and its protein in MKN28 gastric cancer cells, that is mediated by ERK1/2-and p38-dependent pathway.