CXCR4 agonist treatment of hemapoietic cells

A method of reducing the susceptibility of hematopoietic cells to a cytotoxic agent, comprising administering an effective amount of a CXCR4 agonist to the hematopoietic cells prior to or during exposure of the cells to the cytotoxic agent.

A CXCR4 agonist peptide comprising:

• a) an N-terminal sequence homologous to an SDF-1 N-terminal sequence;
• b) a C-terminal sequence homologous to an SDF-1 C-terminal sequence or to a MIP-1α sequence;
• c) a peptide spacer sequence linking the N-terminal sequence to the C-terminal sequence, wherein the peptide spacer sequence linking the N-terminal sequence to the C-terminal comprises naturally-occurring amino acids, non-naturally-occurring amino acids, or both naturally-occurring amino acids and non-naturally-occurring amino acids.