Following identification of PI3K and Src as potential key regulators of chemoresistance in dormant T4‐2 cells, we tested the dose‐dependent response of two breast cancer cell lines—TNBC T4‐2 cells and ER+ MCF‐7 cells—to the Src inhibitor Bosutinib (SKI‐606) and PI3K/mTOR inhibitor Gedatolisib (PF‐05212384). Here, ESR1 is linked to breast cancer.