c-mpl ligand affects circulating and progenitor erythroid cells. (A) Circulating RBCs in AM107, AM1636, and control littermates. AM1636, n = 10; AM107, n = 24; control, n = 23. *P < .001. AM1636 not significantly different from control littermates (P = .14). (B) Bone marrow CFU-E in AM107 and control littermates. Data are presented as % control values (control = 74 ± 21 per 50,000 cells). n = 4. *P < .001.