Indeed, compared with IGHV mutated (M-CLL) cases, the more aggressive U-CLL subtype exhibited an increased expression of cell cycle genes, including ATF2, CCNB2, CDC20, CDC25A, CREB1, E2F4, ESR1, FOXM1, MKI67, MYC, POU2F2, RBL2, SP3, TYMS, UBE2C, VRK1. Here, E2F4 is linked to B-cell chronic lymphocytic leukemia.