As outlined in Fig. 1A, skin KS tumors biopsies from patient volunteers were implanted subcutaneously with extracellular matrix into NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) or human interleukin 6 (hIL6) transgenic NOD.Cg-PrkdcscidIl2rgtm1SugTg(CMV-IL6)1–1Jic/JicTac (hIL6-NOG) immunodeficient mice within several hours of patient resection. Here, CTSG is linked to Kaposi's sarcoma.