α5 integrin has been shown to be expressed in clear cell renal tumors and renal cysts, but not in normal proximal and distal tubules [92], lending some import to the increased α5 integrin levels seen here to correlate with VHL mutations that have a higher RCC risk and suggesting that α5 integrin upregulation might be an early step in tumor initiation. Here, VHL is linked to cystic kidney disease.