GJD2 and retinitis pigmentosa 1: As expected, Cx36 immunosignals were absent in retinas from Rho−/−Cx36−/− (Fig. 1D, J) and rd1Cx36−/− (Fig. 1F, L) mice, allowing to directly test the effect of Cx36-dependent photoreceptor coupling on secondary cone degeneration in RP.