In clear cell renal cell carcinoma (ccRCC), exosomes generated by the tumour cells displayed high levels of TGF‐β1 that caused sustained phosphorylation and subsequent activation of Smad‐2/3 proteins in NK cells leading to a weakened degranulation and killing ability toward target cells after treatment with ccRCC TEXs (Xia et al., 2017). Here, SMAD2 is linked to nonpapillary renal cell carcinoma.