Firstly, considering the aforementioned functions of miR-155 in B-lymphocyte development [60,61] and especially the nature of GC B-cell responses which involve the PU.1 pathway, it is plausible that miR-155 may directly down-regulate the expression of its target PU.1 [63], which is a member of the E26 transformation-specific (ETS) domain-transcription factor family required for later stages of B-cell differentiation and has tumor suppressor activity in B-cells [73]. This evidence concerns the gene SPI1 and neoplasm.