EZH2 and myelodysplastic syndrome: In this model, expression of a mutant enhancer of zeste homolog 2 (EZH2-the catalytic subunit of polycomp repressive complex 2, one of the 10 most frequently mutated genes in MDS (63)) lacking the catalytic SET domain (EZH2-dSET) induces Abcg2 (a drug efflux transporter) up-regulation.