REL and neoplasm: In line with all these observations, administration of Malt1 inhibitors (mepazine, MI-2), IKKβ inhibitor (KINK-1) or c-Rel inhibitors (pentoxifylline, IT-603 or R96A) reduces Treg cell ‘fitness’ in the tumor, i.e., their accumulation and/or their function [48,159,162,167,168].