4-PBA alleviates UPR and ER stress induced by rhodopsin T17M mutant. ARPE-19 cells were transfected with myc-tagged rhodopsin T17M or WT expression constructs and treated with 5 mM 4-PBA. After 24 h, the indicated proteins (a) and splicing of XBP-1(c) were detected by immunoblotting and RT-PCR, respectively. Quantification of the data in (a) and (b) were shown in (c) and (d), respectively. Data were presented as mean ± S.D. *:T17M vs. Control; #: T17M + 4-PBA vs. T17M; **p < 0.01.; *p < 0.05; # p < 0.05.