ESR1 and breast cancer: Phosphorylated proteins that were elevated in the treatment-resistant BC-PDM group (Table 2) included ERα-pSer167, FGFR-pTyr653/654, PI3-kinase p85/p55-pTyr458/199, and IKKepsilon-pSer172, all of which are directly or indirectly related to TAM resistance according to the literature [76–81].