cdc42 deletion in the bone marrow causes lethality and splenomegaly. (A) A schematic representation of the experimental design to delete cdc42 in primary Mx^Tgcdc42^f/f mice by polyI:C induction. (B) Cdc42 protein was absent in bone marrow and spleen from polyI:C-induced Mx^Tgcdc42^f/f mice as detected by Western blotting. (C) Experimental procedures for bone marrow transplantation into lethally irradiated recipient mice. Control (Mx^Tgcdc42^+/+) or mutant (Mx^Tgcdc42^f/f) donor bone marrow cells of the CD45.2⁺ genotype were transplanted into lethally irradiated CD45.1⁺ recipients. After 8 weeks, the recipients were treated with 3 doses of polyI:C in 2-day intervals. (D) The floxed cdc42 allele was effectively deleted from the transplanted Mx^Tgcdc42^f/f bone marrow cells after the polyI:C treatment as detected by PCR genotyping. (E) Viability of the cdc42 knockout primary mice and the bone marrow transplant recipient mice is depicted by the Kaplan-Meier survival curve after polyI:C treatment. Primary Mx^Tgcdc42^f/f (f/f) mice, n = 16; WT mice with f/f bone marrow reconstitution, n = 6; mice with WT bone marrow reconstitution, n = 12. (F) Representative gross anatomy of spleens from polyI:C-treated Mx^Tgcdc42^+/+ (WT) and Mx^Tgcdc42^f/f (KO) mice.