Combinatorial anti-proliferative effects of tamoxifen and naringenin: The role of four estrogen receptor subtypes.

•A single exposure to tamoxifen or naringenin inhibits cell growth at higher doses.•Co-exposure induces cell anti-proliferation in an additive manner in MCF-7 (ER+) cells.•Cell migration inhibition, cell cycle arrest and apoptosis stimulation are involved in those anti-proliferative effects.•Co-exposure down-regulates ERα66, ERα36 and GPR30, but up-regulates ERβ.•Co-exposure modulates the relative ratios of four estrogen receptor subtypes.