In vitro studies showed that DMSO-induced MEL cell erythroid differentiation is associated with reduced expression of the MYC proto-oncogene and that its overexpression inhibited differentiation.63,64 To study the in vivo transforming potential of MYC in the erythroid lineage, Phil Leder and co-workers used regulatory sequences potentially controlling the expression of the erythroid master regulator GATA1 in transgenic mice.49 Diseased mice presented with splenomegaly with significant tumor cell infiltration and erythroid progenitors in the peripheral blood. The gene discussed is GATA1; the disease is Splenomegaly.