Objective:To investigate the effects of ectodysplasin-A1 (EDA1) on the proliferation and cell cycle of ameloblast-like epithelial cells (LS8 cells).Methods:Wild EDA1 plasmid pCR3-Flag-EDA1-W (wild group), syndrome mutant EDA1 plasmid pCR3-Flag-EDA1-H252L (mutant group) and empty vector plasmid pCR3-Flag (control group) were transfected into LS8 cells. Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay and cell cycle was detected by flow cytometry. All tests were repeated three times.Results:Compared with the control group (0.105±0.032), the proliferation activity of the wild group (0.201±0.009) was significantly higher after 72 h ( P<0.05). Compared with the control group (0.168±0.054) and the mutant group (0.194±0.059), the proliferation activity of the wild group (0.386±0.066) was significantly higher after 96 h ( P<0.05). There was no significant difference between the mutant group and the control group at all time points ( P>0.05). In the G 0/G 1 phase, compared with the control group (65.4%±2.1%) and the mutant group (66.6%±3.1%), the cell distribution ratio of the wild group (51.2%±1.1%) was significantly lower ( P<0.01). In the S phase, compared with the control group (23.1%±2.0%) and the mutant group (21.9%±1.8%), the cell distribution ratio of the wild type group (37.3%±2.4%) was significantly higher ( P<0.01). There was no significant difference in cell cycle distribution between the mutant group and the control group ( P<0.05). Conclusions:Wild EDA1 promotes the proliferation of LS8 cells and the transformation from G 0/G 1 to S phase. The syndrome mutant EDA1 (EDA1-H252L) loses its function of regulating the cell proliferation and cell cycle of LS8 cells.