Fascaplysin arrested the cell cycle of A549 cells by regulating cycle-related proteins. (A) Cell viability was measured by CCK-8 assay after treatment of A549 cells with different doses of fascaplysin for 24 h. (B) Representative images of A549 cell colony formation after treatment with fascaplysin. (C,D) Representative results of cell cycle and quantitative analysis. Data are presented as mean ± SD of three independent experiments compared with control. * p < 0.05, *** p < 0.001, and **** p < 0.0001. (E) We examined the expression of cell cycle-related proteins by Western blotting after treating A549 cells with fascaplysin (0, 0.5, 1, and 2 μM) for 3 h.