Synergistic effects of octylphenol and isobutyl paraben on the expression of calbindin-D₉k in GH3 rat pituitary cells.

Endocrine disruptors (EDs) have estrogenic activity and can cause physiological estrogenic responses. Octylphenol (OP) is one of the alkylphenolic compounds known as environmental xenoestrogens because they strongly compete with endogenous estrogens to bind to estrogen receptors (ERs). Isobutyl paraben (IBP), a widely used preservative, also exhibits estrogenic activity.