HTRA1 and age-related macular degeneration: To investigate the involvement of ARMS2/HTRA1 in affecting the SOD2 defense in RPE as reported by Yang et al., we measured the expression levels of superoxide dismutase 2 (SOD2) in AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE compared to normal RPE-iPSC-RPE by Real-Time PCR under normal and our established chronic stress conditions by incubation of the cells for 2 h with H2O2 at 0.4 mM for 5 consecutive days.