RAF1 and Burkitt lymphoma: Thus, the well-known RAF->MEK->ERK-|RAF regulatory loop also exists in BLs and DLBCLs, whereas the negative impact of BCR mediated p38 activation onto this loop is a newly discovered crosstalk found in three BL cell lines BL-2, BL-41 and CA-46 and one DLBCL cell line HBL-1.