DCLK1 and nonpapillary renal cell carcinoma: Intriguingly, unlike the predominant upregulation of the DCLK1-S isoforms in colorectal cancer and esophageal squamous cell carcinoma, ccRCC shows substantial upregulation of DCLK1-L variants [22, 23], suggesting a potential cancer-specific activation of α-promoter in ccRCC.