CREB1 and B-cell chronic lymphocytic leukemia: 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.