Photomicrographs of murine marrow cells expressing Mpl fusion proteins.

Cells transduced with either the membrane-tethered Mpl construct (left panel) or the cytoplasmic Mpl construct (right panel) were cultured in the presence of AP20187 (100 nM) for 102 days, then photographed. Magnification: top panels, × 40; bottom panels, × 100.