When tested in the cotransfection assay without DAF-9, two di- astereomers of 26-hydroxy-4-cholesten-3-one (( 25S),26- hydroxy-4-cholesten-3-one and (25R),26-hydroxy-4-cho- lesten-3-one) were strongly active (Figure 3B).
The ring A oxysterols were inactive, confirming the idea that DAF-12 ligands require a 3-keto group.