Btk and Syk inhibitors abrogate FL BCR activation induced by M2 macrophages. Purified Hi-B FL cells were pretreated with Ibrutinib, R406, or their solvent (DMSO) before coculture or not (0) with M2 macrophages (M2) for 1 hour. B cells were then collected and (A) pSYK, (B) pAKT, (C) pERK, and IgM expressions were studied by western blot. Bars represent mean ± SD from 2 experiments.