DLG5 and breast cancer: The relationship between DLG5 expression and TAM resistance in ER+ breast cancer was firstly analysed by a gene expression profile in the GEO database (GSE26459), which showed that DLG5 expression in the TAM‐resistance MCF7 cells was significantly lower than that in the TAM‐sensitive MCF7 cells (P < 0.01, Figure 1A).