Figure 4. Co-treatment with esketamine and 5-FU promotes apoptosis in colon cancer cells. (A) Flow cytometry analysis of Annexin V/PI staining in DLD1 and HCT15 cells treated with esketamine (1 mM), 5-FU (30 µM), or their combination for 48 h. The quantifications of apoptotic cells are shown. (B) Western blot analysis of the indicated apoptosis-related proteins. GAPDH served as the loading control. Data are presented as the mean ± SD (n = 3 independent experiments). ***p < 0.001, ****p < 0.0001.