Effect of SPRY4-IT1 on the cell cycle and apoptosis of breast cancer cells in vitro. MDA-MB-231 and MDA-MB-435S cells were transfected with si-SPRY4-IT1 and si-NC, respectively. (A) The bar chart represents the percentage of cells in the G0/G1, S, or G2/M phase, as indicated. The data are presented as the means ± SD from three independent experiments. *P < 0.05. (B) After SPRY4-IT1 knockdown in MDA-MB-231 and MDA-MB-435S cells, the cyclinD1 protein level is diminished compared with the level observed in the control group, as determined by western blot analysis. (C) The percentage of apoptotic cells was determined by flow cytometric analysis. The data represent the means ± SD from three independent experiments. *P < 0.05. (D) Apoptosis in MDA-MB-231 and MDA-MB-435S cells after SPRY4-IT1 knockdown was detected through TUNEL staining. (E) The Bax and Bcl-2 protein levels were elevated in MDA-MB-231 and MDA-MB-435S cells after SPRY4-IT1 expression was blocked compared with the control group.