Patent ID: 7067118

Claim:
A method of inducing cellular expansion, comprising the steps of: isolating a population of cells to be expanded; and exposing said cells to a soluble mutant flt3-L polypeptide to produce an expanded cell population, wherein said polypeptide comprises a substitution at one or more residues corresponding to amino acid position 24 of the full length human wild type flt3-L polypeptide (SEQ ID NO:1) or amino acid positions 8–15, 81–87 or 116–124 of the mature human wild type flt3-L polypeptide (SEQ ID NO:18), wherein the mutant flt3-L polypeptide exhibits increased biological activity relative to full length wild type (SEQ ID NO:1) or mature human wild type (SEQ ID NO:18) flt3-L polypeptide.