Fig. 1. Potential mechanisms of phthalate esters on endometrial cells.

DEHP acts on hormone receptors, such as ER and PR, and activates several inflammatory enzymes. These change the signaling pathways including MAPK/Erk and NF-kB, and release enzymes such as MMP-2/9, Pak4 and PG. Also, DEHP causes oxidative stress, reduces antioxidant enzymes such as SOD, GPx, HO, and CAT, and increases ROS. The interaction of all these changes increases the viability, resistance and proliferation of cells outside the uterus causing endometriosis. DEHP, di-2-ethylhexyl phthalate; ER, estrogen receptor; PR, progesterone receptor; MAPK, mitogen-activated protein kinase; Erk, extracellular signal-regulated kinase; NF-kB, nuclear factor kappa-light-chain-enhancer of activated B cells; MMP, matrix metalloproteinase; Pak4, p21-activated kinase 4; PG, prostaglandin; SOD, superoxide dismutase; GPx, glutathione peroxidase; HO, heme oxygenase; CAT, catalase; ROS, reactive oxygen species.