(A) LX2 cells were incubated for 30 min with NRB-AF12 or ER-Tr green; after replacing the staining solution with probe-free medium, evaluation of NRB-AF12 and ER-Tr extent of fluorescent signal and photostability was performed. (B) LX2, (C) HSC-T6, and (D) HepG2 cells were treated for 24 h with increasing doses (0.1, 1 and 10 μM) of NRB, NRB-AF12, glibenclamide or ER-Tr. Compounds toxicity was evaluated by trypan blue exclusion test of cell viability. NT, not treated cells.