Figure 1. Per2 circadian expression in retina and retinal pigment epithelium (RPE). A: RPE in Light/Dark cycle. B: Retina in Light/Dark cycle. C: RPE in constant darkness. D: Retina in constant darkness. In both tissues, the Per2 mRNA levels showed a significant circadian rhythm (one-way ANOVA, p<0.05 in all cases). Each point represents the mean±SEM (n=3–7).