MMP2 and T-cell non-Hodgkin lymphoma: Intriguingly, two studies found that H3K4 trimethyltransferase complex was recruited on the MMP9 promoter in T-cell lymphoma cells, and knockdown of MLL showed reduced MMP2 and MMP9 in melanoma cells [35, 36], which enabled us to suspect that reduced MLL and H3K4 trimethylation was responsible for low expression of MMP2 in cell lines with MLL translocation.