Analysis of the cell-intrinsic effects of Srf deletion. (A) Experimental outline of transplantation experiments. Srf^{flx/flx;Mx1-Cre} whole BM cells (CD45.2, 4 × 10⁶ totals) were transplanted into 6-week-old lethally irradiated wild-type littermate recipients (CD45.1). The recipients were treated or not with pIpC 4 weeks postengraftment to induce Srf-deletion exclusively in hematopoietic cells and not in BM stromal cells. Mice were analyzed 5 weeks after Cre induction. (B) Table of the hematologic parameters, BM cellularity, and spleen weight. Values shown are mean ± SEM (n = 7 per group, ***P < .001 by Mann-Whitney test). (C) Cell autonomous expansion of the LSK and MP compartments in recipient mice treated or not with pIpC. (n = 7 per group, *P < .05). (D) BM (2 × 10⁴), spleen (2 × 10⁵) and PB (5 × 10⁵) cells of recipient mice treated or not with pIpC were plated in methylcellulose medium and scored for CFU-Cs after 7 days (n = 7 per group, *P < .05 and **P < .01).