Flt1 protein expression.

(A) Flow cytometry analysis of Flt1 expression in HPCs differentiating along the Mk and Mo lineages. Results of a representative experiment are shown. (B) Immunocytochemical analysis of Flt1 in (i) Mo and (ii) Mk cells. Panels labeled “C” are negative controls. (Bi) Flt1 panels show expression in PB monocytes. (Bii) Flt1 panels show expression in day 6 Mk precursors.