The IHC expression of CD44 in primary and metastatic RCC tumours and adjacent normal tissue is shown in Figure 10A. Adjacent normal kidney tissue showed negative staining in the glomerulus and moderate cytoplasmic CD44 staining in the tubules, while a distinct membranous and moderate cytoplasmic staining was observed in primary ccRCC (Figure 10A). Here, CD44 is linked to nonpapillary renal cell carcinoma.