However, sustained inhibition of EGR1 with siRNA or tolfenamic acid (TOLE) suppressed the growth of endocrine resistant breast cancer cells and interacted synergistically with both 4-hydroxytamoxifen (hereafter referred to as TAM), major active metabolite of tamoxifen, and ICI in inhibiting cell proliferation. The gene discussed is EGR1; the disease is breast carcinoma.