Mice expressing Ptpn11^D61Y develop fatal MPD. (A) Schematic of LSL-Ptpn11^D61Y allele with floxed “STOP” cassette (top) and expressing the Ptpn11^D61Y mutation after Cre expression (bottom). (B) Kaplan-Meier analysis of a cohort of Ptpn11^D61Y mice (n = 25) and littermate controls (n = 32). Cumulative survival was plotted against days after treatment with pIpC. Ptpn11^D61Y mice have a median life span of 45 weeks. (C-D) Ptpn11^D61Y mice develop splenomegaly (C) and hepatomegaly (D). (*P < .05.)