Fig. 4.

Downregulation of NAMPT/NAD involved in cell cycle arrest in A549 cells receiving MAN treatments. (A) NAC and NMN co-treatments restored phase S decline in cells induced by MAN stimulus. (B) regulatory effect of MAN on critical signals involved in cell cycle progression control: (a) MAN regulated the expressions of p-p38, p-p53, CDK4, and cyclin D1 in a concentration-dependent manner. (b) NAC and NMN reversed the regulation of MAN on cell cycle–related proteins. (c) Quantification of immunoblotting assay. Data are expressed as means ± SD (n = 3). Statistical analyses were performed using the SPSS and differences among different groups were evaluated using ANOVA followed by Tukey post hoc test. *P < 0.05 compared with MAN-treated cells; **P < 0.01 compared with MAN-treated cells