SIRT1 and age-related macular degeneration: Considering the lower expression levels of PGC-1α/SIRT1 in the diseased AMD cells48, the resilience of the SIRT1/PGC-1α pathway in Nic-ARPE-19 cells, as well as the polarized basolateral secretion of VEGF (Fig. 2B,C), may support the notion that the smaller cells in the cell clusters here designated would be functionally integral hRPE cells.