ESR1 and breast cancer: Targeting autophagy was used to circumvent TRAIL-resistance in tumors with apoptosis defects; knockdown of autophagy, in combination with tamoxifen or 4-hydroxy-tamoxifen (4-OH-T), resulted in decreased cell viability of two human hormone-dependent breast cancer cell lines, ER-positive MCF-7 [70, 88] and T-47D cells [89].