Notch1 but not Notch2 is primarily responsible for Notch-induced lymphoid differentiation. CD34⁺CD38^– cord blood cells were transduced with either Notch1, Notch2, or control shRNA constructs and cultured in the presence of increasing concentrations of immobilized Delta1^ext-IgG. After 4 days, cells were GFP sorted and replaced in culture. After 7 days, cells were harvested to prepare lysates or immunostain for FACS analysis. (A) Lysates were separated with sodium dodecyl sulfate–polyacrylamide gel electrophoresis, transferred to nitrocellulose, and immunoblotted with the α-Notch1 monoclonal antibody, MN-1, stripped, and reimmunoblotted with the anti-Notch2 monoclonal antibody, BHN6. (B) Cells were assessed for CD7 and CD34 expression. Numbers in corners are the percentage of gated events within that quadrant.