Cell-autonomous requirement for Ptpn11 in HSC maintenance. (A) Lethally irradiated CD45.1⁺ recipients were transplanted with 10⁶ BM cells from Mx1-Cre;Ptpn11^+/+ (n = 6), Mx1-Cre;Ptpn11^flox/+ (n = 4), or Mx1-Cre;Ptpn11^flox/flox (n = 4) mice, along with 10⁵ wild-type CD45.1⁺ cells. After 5 weeks of engraftment, chimeric mice were treated with 5 doses of pIpC, and the percentage of peripheral blood cells expressing CD45.1 and CD45.2 was quantified by flow cytometry at the indicated times. *P < .05, analysis of variance. (B) Levels of CD45.1⁺ BM Lin⁻c-kit⁺ progenitors (LK) and peripheral blood B220⁺, CD3⁺/CD4⁺/CD8⁺, and Gr1⁺ cells were quantified 21 weeks after pIpC induction. *P < .05, analysis of variance. (C) Lethally irradiated Mx1-Cre;Ptpn11^flox/+ (n = 4) and Mx1-Cre;Ptpn11^flox/flox (n = 4) control recipients were transplanted with 10⁶ BM cells from wild-type CD45.1⁺ donors. Mice were treated and analyzed as described in panel A.