CD81 and kidney cancer: Other less prevalent malignant kidney tumors included a renal cell carcinoma (RC), which showed a CD271+ CD81+ EpCAM+ CD71+ CD117+ phenotype in the absence of CD9, CD10, CD58, CD90, CD105, and GD2, and a clear cell sarcoma, which expressed CD271+ and GD2+ without EpCAM (Figure 3 and Table S2).