Neutrophils from Mll5^−/− mice are functionally impaired. (A) Cytospin preparation of BM cells from 5-month-old wild-type (left, original magnification ×400) and Mll5^−/− (right, original magnification ×200, inset ×400) animals stained with Wright Giemsa stain. Quantification of the oxidative burst activity of neutrophils in peripheral blood (PB) of Mll5^+/+ and ^−/− mice. (B) Percentage of neutrophils producing reactive oxidants and (C) enzymatic activity of reactive oxidants per cell. (D) Eight-week-old Mll5^−/− mice have increased numbers of granulocyte progenitors; graph depicts mean and SD of 10-day G-CSF–responsive colony-forming cells formed per 10⁵ bone marrow cells.