CR4 inhibits tissue infiltration of Ph⁺ ALL cells in vivo. Tissue-touch preparations were prepared from the organs of CR4-treated and control mice after 3 weeks and stained with Wright-Giemsa stain. The spleen, liver, and kidney of control mice demonstrate significant infiltration with ALL blast cells, whereas CR4-treated organs are essentially normal and devoid of ALL cells. Original magnification, × 400. Arrows indicate blasts.