FOXO3 and cancer: Nevertheless,we have recently identified (4-propoxy)phenylpyrimidinylguanidineas a FOXO3 inhibitor in cancer cells in the low micromolar range.Here, we report the synthesis and structure–activity relationshipstudy of a small library of its derivatives, some of which inhibitFOXO3-induced gene transcription in cancer cells in a submicromolarrange and are thus 1 order of magnitude more potent than their parentcompound.