Our study showed that PEITC was able to cause a rapid decrease in MCL-1 protein in p53-null CLL cells within 2–5 hours after drug incubation, whereas treatment with 10 μM F-ara-A for 48 h did not cause any significant decrease in MCL-1 (Figure 6A). The gene discussed is MCL1; the disease is B-cell chronic lymphocytic leukemia.