Given that several of these factors are known to increase the numbers of mCECs and CEPs in the circulation of human subjects (Kalka et al, 2000; Beaudry et al, 2005; Farace et al, 2007), we compared the CEC counts in healthy control subjects with those in patients with VHL with and without RCC and in patients with sporadic RCC. The gene discussed is VHL; the disease is renal cell carcinoma.