CYP27B1 and neoplasm: To further confirm that our identified TAD fusion across the CYP27B1 locus would change this promoter–enhancer chromosomal looping, a 3C assay demonstrated that a novel chromosomal loop between the CYP27B1 P2 promoter and its distal potential E2 enhancer formed in both WERI-RB1 and Y79 tumor cells (Figure 5E, lanes 2–3) compared with that in ARPE19 cells (Figure 5E, lane 1).