Corrective effects of ERK1/2 deficiency on the MPN phenotype were enhanced in secondary recipients with normalization of red cell parameters (Supplementary Fig. 4A-E) and progressive loss of the Jak2V617F clone in blood and BM stem/progenitor populations (Supplementary Fig. 4F-J). The gene discussed is MAPK3; the disease is myeloproliferative neoplasm.