CLOCK and B-cell chronic lymphocytic leukemia: Rana et al. [30] investigated the expression of four circadian clock genes (PER1, PER2, BMAL1, and CLOCK) and three clock-controlled cell cycle genes (Wee1, Cyclin D1, and Myc) in 37 patients with chronic lymphocytic leukemia (CLL) and an equal number of healthy controls.