AR and breast cancer: 19 These authors noted that the gene maps to a region that is frequently lost in many cancers including breast cancer.19 PATs specifically implicated in breast cancer include ZDHHC7 and ZDHHC21, which are responsible for the palmitoylation of the sex steroid receptors estrogen (ER), progesterone (PR), and androgen (AR);20 ZDHHC17 and ZDHHC20, upregulated in breast cancer cells;21,22 and ZDHHC9, which induces hyperproliferation when overexpressed in the premalignant breast cancer cell line MCF10AT.23