11β-PGF1β is the stereoisomer of PGF1α with both C-9 and C-11 hydroxyls inverted. There are no published reports on the biological activity of this compound. 11β-PGF1β is the stereoisomer of PGF1α with both C-9 and C-11 hydroxyls inverted. There are no published reports on the biological activity of this compound.