 Similarly, prostacyclin (PGI2) synthase (PGIS) converts PGH2 into PGI2.A thromboxane synthase (TxAS) has also been identified.Prostaglandin-F synthase (PGFS) catalyzes the formation of 9α,11β-PGF2α,β from PGD2 and PGF2α from PGH2 in the presence of NADPH.