As shown in (Fig. 1A), the normal cell lines (RPTEC and HK-2) expressed TGF-β1, PD-L1 and VEGF at relatively low levels, which was expected since TGF-β1, PD-L1 and VEGF are over-expressed in various types of cancer including ccRCC and expressed at low levels in normal tissues [29–31]. Here, TGFB1 is linked to cancer.