Immunoblotting.

To quantify protein levels inside cultured iRPE cells, cells were lysed and homogenized with RIPA buffer (Thermo Scientific, #89900) for extracting total protein. The supernatant was collected for Sodium dodecyl-sulfate (SDS)–polyacrylamide gel electrophoresis with 10% protein gel (Bio-Rad, #4561083). The targets were blotted with anti-ARMS2 antibody at 1:1,000 (OriGene, #TA812774), anti-HTRA1 1:500 (Abcam, #ab274322), anti-SOD1 1:1,000 (Novus Biologicals, #NBP2-24915), anti-SOD2 1:1,000 (Abcam, #ab13533), anti-LRAT (Novus Biologicals, #NBP2-50444), and anti-RPE65 1:1,000 (Novus Biologicals, #NB100-355SS). The blotting signals were visualized by an iBright FL 1500 Imaging System (Thermo Fisher Scientific).