Given that scRNA-seq results suggested that loss of Frmd8 reduced the proportion of Hsd epithelial cells and the expression of Esr1 and Pgr, multiple immunofluorescence staining analyses were then performed to examine the change of ERα and PR at the protein levels in situ in mammary tumors of 4-month-old Frmd8-depleted mice. This evidence concerns the gene FRMD8 and breast cancer.