● AIM: To investigate the effect of high mobility group protein box-1(HMGB1) si RNA on proliferation and apoptosis of retinoblastoma(Rb) cells. ● METHODS: The expression of HMGB1 in Rb cells were detected by real-time polymerase chain reaction(RT-PCR) and Western blot. Chemically synthesized HMGB1 si RNA was transfected into Y79 cells. The inhibitory rate was also examined by RT-PCR and Western blot. After HMGB1 si RNA transfection, the cell proliferation was analyzed by MTT, and cell apoptosis was detected by Caspase-3 active detection kit. Cell cycle distribution and apoptosis were detected by flow cytometry.● RESULTS: The expression of HMGB1 significantly elevated in Rb cells(P<0.01). After transfected by si RNA, the HMGB1 protein level of Y79 cells was significantly reduced(P<0.01). After si RNA interference HMGB1, the proportion of proliferating cells reduced, and the proportion of quiescent cells increased(P <0.05). In addition, apoptosis rate of Y79 cells increased from 2.03% to 9.10% after interfering with HMGB1 si RNA(P<0.05).● CONCLUSION: Specific HMGB1 si RNA can inhibit the expression of HMGB1. The effect may be attributed to inhibit the proliferation and promote cell apoptosis. ● AIM: To investigate the effect of high mobility group protein box-1 (HMGB1) si RNA on proliferation and apoptosis of retinoblastoma (Rb) cells. · METHODS: The expression of HMGB1 in Rb cells were detected by real-time polymerase chain reaction The inhibitory rate was also examined by RT-PCR and Western blot. The HMGB1 si RNA was transfected into Y79 cells. The inhibitory rate was also examined by RT-PCR and Western blot. After HMGB1 si RNA transfection, the cell proliferation was analyzed by MTT, and cell Apoptosis was detected by Caspase-3 active detection kit. Cell cycle distribution and apoptosis were detected by flow cytometry. RESULTS: The expression of HMGB1 significantly elevated in Rb cells (P <0.01). After transfected by si RNA, the HMGB1 protein level The proportion of proliferating cells reduced, and the proportion of quiescent cells increased (P <0.05). In addition, the apoptosis rate of Y79 cells increased from 2. 03% to 9.10% after interfering with HMGB1 si RNA (P <0.05). CONCLUSION: Specific HMGB1 si RNA can inhibit the expression of HMGB1. The effect may be attributed to inhibit the proliferation and promote cell apoptosis.