PRKN and ovarian carcinoma: To determine whether regulation of PINK1 stabilization by EIF2AK1 is generalizable to other cells, we screened a panel of human cell lines including SK-OV-3 ovarian cancer cells that express high levels of endogenous PINK1 and Parkin (4, 24), U2OS osteosarcoma cells that express moderate PINK1 and low levels of Parkin, and ARPE-19 retinal pigment epithelial cells that have moderate PINK1 expression and no Parkin similar to HeLa cells (fig.