(A–C,E,F) Evaluation of SnMP (5 µM, 10 µM) effects on HO-1, HO-2, G6PD and TIGAR protein levels on A549 cells. (D) Measurement of HO enzymatic activity in A549 cells after 5 µM and 10 µM SnMP treatment (** p < 0.01, *** p < 0.001 vs. CTRL). Results are expressed as mean ± SEM.