RB1 and breast neoplasm: Patients with primary breast tumors that had high phosphorylation of ER-α Ser167, or high expression of ER-α (1D5), PR (636), PRA, or PRB, significantly responded to endocrine therapy (Mann-Whitney U test, P = 0.033, P = 0.0045, P = 0.0008, P = 0.0001, and P = 0.013, respectively).