FOXO4-DRI is a synthetic version of FOXO4, containing D amino acids instead of L amino acids. This modification is intended to allow the peptide to retain the functionality of the original protein but with a longer shelf life and lower clearance. Its most prominent function has been suggested to regulate apoptosis in senescent cells.^[1] It has been suggested in scientific studies that senescent cells might exhibit resistance to apoptosis, aka programmed cell death. This resistance has been associated with increased binding of FOXO4 with another protein, p53, which should trigger apoptosis but become inactivated.