IL4 and B-cell chronic lymphocytic leukemia: In an attempt to understand how ruxolitinib turned up NFκB-regulated genes and plasma TNFα proteins while decreasing phospho-STAT3 (13), IFN-stimulated genes, and plasma IL-10 in vivo (Figure 1 and Supplementary Figure 1), CLL cells were purified from blood and cultured as described previously on OP9 stromal cells or OP9 cells engineered to express CD40L along with IL-4 (20) in the presence of absence of ruxolitinib at 500 nM, a dose that approximates therapeutic plasma concentrations (27).