Fig. 4

Nicotine activates the prok2R/Akt/FoxO3a axis and exhibits anti-apoptotic effects against MPP⁺ in the HEK293T cell line. Western blot (WB) images (a) and semi-quantitative analysis (b–d) of prok2R/Akt/FoxO3a axis. Confocal laser scanning microscopy (CLSM) images of fluorescein isothiocyanate (FITC)-labeled prok2R (e) and semi-quantitative analysis of fluorescence intensity (f). Scale bar = 10 μm. The expression levels of anti-apoptotic protein (Bcl-2), pro-apoptotic protein (Bax), and apoptotic executor protein (Cl-casp3) detected using WB (g–j). k, l CLSM of FITC-labeled Cl-casp3 indicating decreased expression levels after nicotine treatment against MPP⁺ damage. Scale bar = 10 μm. Significant differences are shown by *p < 0.05, **p < 0.01, ***p < 0.001. n = 3 in each group