To evaluate the functional integrity of the p53 pathway in the resistant samples with wild-type TP53 (without del17p), a Western immunoblot was performed for three resistant (RG7388 LC50 > 10 μM) CLL samples with SF3B1 mutation, and three sensitive (RG7388 LC50 = 0.57 ± 0.17 μM) CLL samples without SF3B1 mutation (Figure 4A). This evidence concerns the gene SF3B1 and B-cell chronic lymphocytic leukemia.