To search for M4-macrophage in urethral tissues in HIV/AIDS, we analyzed the frequency of total mucosal (CD68+) macrophages in urethral cell suspensions and therein, the frequency of M4-macrophages (S100A8+MMP7+) by flow cytometry (Fig. 1c, d and Supplementary Fig. 3). The gene discussed is S100A8; the disease is AIDS.