CLIP4 and nonpapillary renal cell carcinoma: Our previous studies have demonstrated that forkhead box protein C2 (FOXC2) and cytoskeleton-associated, protein-glycine (CAP-Gly)-rich, domain-containing linker protein family member 4 (CLIP4) mutations were associated with early-stage ccRCC, and a synchronous metastasis [10] and validation study confirmed that PBRM1, BAP1, and FOXC2 were shown to be significantly associated with aggressive early-stage ccRCC through target sequencing and immunohistochemistry [5].