E2F1 and cancer: We first examined the transcriptional changes via qRT-PCR of the ARPE-19 cells 1 day after 60 min of 222-nanometer far-UVC illumination and focused on tumor-suppressor genes (Rb1 and P53), cancer-related genes (SNAI1, E2F1, E2F2, and CDK4), and stress-related genes (BMP4, NRF2, p21, IL6, and HIF1A) (Figure 4A).