STAT3 and mantle cell lymphoma: In MCL cells, these experiments revealed comparable, though more variable, effects of CK2 inhibitors on these pro-survival signaling pathways, since CX-4945 and K27 caused a marked reduction of phospho Ser727 STAT3 and phospho Ser529 p65 in all the three MCL cell lines, which appeared milder in Granta-519 cells (Figure 5H).