Splenic infiltration in Mx1-Cre, Nf1^flox/flox, beta c^−/− and Mx1-Cre, Nf1^flox/flox, beta c^+/+ mice. (A) Inactivation of Nf1 leads to increased numbers of myeloid lineage cells in spleen and liver, which is most pronounced in 6 Mx1-Cre, Nf1^flox/flox, beta c^+/+ animals and absent in 7 wild-type and 5 beta c^−/− spleens. (B) Spleen weights in 7 control and 6 Mx1-Cre, Nf1^flox/flox mice. Loss of Nf1 results in splenomegaly and is attenuated 6 Mx1-Cre, Nf1^flox/flox, beta c^−/− mice. (C) CFU-GM colony numbers from 4 individual experiments of mice of all 4 genotypes demonstrate infiltration in the Nf1 mutant animals.