ESR1 and breast cancer: STK33 expression analysis revealed markedly higher levels in TNBC cell lines (MDA‐MB‐231 and HCC1806) compared to ER (+) (MCF‐7 and T47D) and HER2 (+) (SK‐BR‐3 and JIMT1) breast cancer cell lines, where expression was nearly undetectable (Figure S2C, Supporting Information).