BCL2 and lymphoma: Although several BCL2-engineered models have provided the initial proof-of-principle that BCL2 ectopic expression leads to FL and high-grade lymphomas, the expression of BCL2 in all B cells (and all T cells for some models) do not represent a true premalignant intermediate stage seen during human lymphomagenesis, where the first t(14;18) event occur in a single B cell in the BM, and is carried on until its ectopic expression in the GC.