MUC3A and nonpapillary renal cell carcinoma: Tian Niu, Xu Zhiying et al. detected high expression of MUC3A and MUC13 in patients with non-metastatic ccRCC by tissue microarray and immunohistochemistry and found that the expression of MUC3A and MUC13 was positively correlated with Fuhrman classification [81,82].