In addition, in spite of positive immunohistochemical staining for ESR1 protein in all in vitro cell cultures, addition of 17β-estradiol, 4-androstene-3,17-dione or drugs targeting the estrogen-signaling pathway did not have a significant effect on the proliferation of the conventional central chondrosarcoma cell cultures. The gene discussed is ESR1; the disease is chondrosarcoma.