Table 3.

Proposed functions for Hoxa9 and Meis1 in normal HSP and LCP, based on the function of Hoxa9 in immortalized SCF-dependent myeloid progenitor cell lines, and of Meis1 in the Meis1/Hoxa9-immortalized myeloid-lymphoid progenitors that express unique ST-HSC genes

Function in SCF-dependent progenitor cell lines	Proposed function in HSP and LCP in vivo
Hoxa9
Maintains genetic program specifying self-renewal	Positively regulates self-renewal
Meis1
Stimulates proliferation	Positively regulates proliferation
Prevents differentiation by G-CSF	Suppresses premature differentiation by lineage-specific cytokines
Induces expression of FLT3, IL-7R, CD27	Positively regulates proliferation/differentiation response by controlling the abundance of receptors for cytokines
Induces expression of CD34, Itgβ7, C1qR1	Regulates homing and migration by controlling the levels of proteins that bind sugars and extracellular matrix proteins