Morphologic evidence of MF in the BM and spleen of mice receiving ERK2-DBP–mutant HSPCs. (A-B) Hematoxylin and eosin and reticulin staining of representative BM sections from mice that received ERK2-WT–, -KO– and -DBP–mutant HSPCs, at 12 weeks after BM transplant. (B′) Enlarged images delimited by the blue inset in panel B. Scale bars, 20 µm. (C-D) Representative images of sections of spleen from the mice above, stained with hematoxylin and eosin (C) or reticulin (D) 12 weeks after BMT. Scale bars, 50 µm.