KMT2D and metabolic dysfunction-associated steatohepatitis: To test whether MLL4 expressed in macrophages plays an important role in NASH development, we next generated myeloid cell-specific Mll4 knockout mice, the Mll4f/f; LysM-Cre (Mll4-LKO), by crossing Mll4f/f mice with mice carrying a Mll4f/+;LysM-Cre transgene.