Rotenone inhibited the tumourigenesis in nude mice. LoVo cells were transfected with PI3K overexpressing vector, then LoVo cells were subcutaneously inoculated into nude mice. To observe the effect of rotenone on tumourigenesis in nude mice, rotenone (1 mg/kg) was intraperitoneally injected into the mice every other day. So, nude mice were divided into control group, Rot group, PI3K group and PI3K + Rot group, with five mice in each group. Six weeks later, mice were sacrificed and tumour tissues were collected. A, Tumours collected from mice in the four groups. B, Tumour volumes at day 14, 21, 28, 35, 42 in the four groups. C, Tumour weight in the four groups. D, The apoptosis was detected in tumour tissue using TUNEL assay. E, The expression of vimentin was detected using immunohistochemistry. F and G, The protein levels of p‐PI3K, PI3K, p‐AKT, AKT, epithelial marker E‐cadherin, mesenchymal markers Vimentin and N‐cadherin were detected by western blot. **P < .01, ***P < .001 vs control. NS P > .05 vs PI3K group. B, , PI3K + Rot; , PI3K; , Rot; , control; F and G, , control; , Rot; , PI3K; , PI3K + Rot