MAPK3 and retinal degeneration: As controls, we used ERK1−/−; Erk2f/f mice treated with PBS (CTL), ERK1−/−; Erk2f/f mice treated with Dox, and VMD2-rtTA/TRE-Cre; ERK1−/−; Erk2f/f mice treated with PBS; none of these mice showed retinal degeneration (data not shown).