4-PBA facilitates rhodopsin T17M degradation and inhibits apoptosis induced by rhodopsin T17M. (a) ARPE-19 cells were transfected with myc-tagged rhodopsin T17M and untreated by 4-PBA (control) or treated by 5 mM 4-PBA. After 36 h, cells were treated with cycloheximide for the indicated time points and the proteins were detected by immunoblotting. (b) Quantification of the proteins shown in (a). Data were presented as mean ± S.D. *p < 0.05. (c) ARPE-19 cells were stained with annexin V and PI. The apoptotic cells were annexin V-positive. (d) Quantification of apoptotic cells. Data were presented as mean ± S.D. *p < 0.05, compared with control.