PTGES and colon carcinoma: Interestingly, this secreted PGF2α was able to increase mPGES1 but also COX-2 in colon carcinoma cells, via FP receptor and EGR1, further enhancing PGE2 levels indicating a positive feedback loop between COX-2/mPGES1/PGE2 and PGF2α (Stamatakis et al., 2015).