KFLS cells from Hoxa-9-deficient marrow have a reduced number of high-proliferative potential (HPP) colonies. Single KFLS cells (Figure 3) were sorted into individual wells of a 96-well plate containing media with a combination of cytokines (see “Materials and methods”) and cultured for 10 days. (A) Colonies were enumerated in each well according to type (GM [granulocyte-monocyte], mixed, BFU-E, and HPP). (B) Typical colony formed by Hoxa-9^-/- KFLS cell. (C) HPP colony formed by wild-type KFLS cell. Colony images were obtained using an Axiovert 25 inverted microscope equipped with an Axioplan 32 ×/0.40 objective lens (Carl Zeiss, Thornwood, NY). Images were captured with a Nikon Coolpix 4500 digital camera (Nikon USA, Torrance, CA) and enhanced using Nikon Photoimpression 4.0 software.