In a separate study, PRP4K was also identified as an estrogen-regulated gene, and that treatment of cells with 4-hydroxy-tamoxifen (4-OHT), the active metabolite of the anti-estrogen drug tamoxifen, resulted in both reduced PRP4K expression and an increase in taxane resistance in MCF7 breast cancer cells expressing the estrogen receptor 1 (ESR1) (Lahsaee et al., 2016). The gene discussed is ESR1; the disease is breast cancer.