Model of HSPC self-renewal and differentiation. Notch2 affects HSPC self-renewal by blocking differentiation into multipotent progenitors (MPP) and myeloid/monocytic (M) cell lineage. Notch1 promotes T-cell (T) differentiation versus B-cell (B) differentiation. Also illustrated are molecules with proposed roles in HSPC self-renewal and expansion. Factors with proposed anti-apoptotic and enhanced homing/in vivo survival effects (eg, PGE2) on HSPCs are not shown.