JAK2 and B-cell chronic lymphocytic leukemia: When CLL cells were cultured on BMSC layers, the mortality caused by ibrutinib is hampered (Figure 5C, column ibrutinib 2.5 μM, fold induction, alone 1.25 ± 0.31 vs. BMSCs 1.03 ± 0.34, p = 0.0186, Wilcoxon matched-pairs signed rank test), likely related to activation of JAK2/STAT3 signaling as previously demonstrated in this work (Figure 2).