EPO and hepatocellular carcinoma: There is evidence that HCC produces marked erythrocytosis and is associated with increased levels of serum Epo or the production of Epo-like activity in cell cultures.27, 28 Because HCC is a hypervascular tumour and the liver and kidney are major Epo production sites, it is suggested that Epo signalling may contribute to the development and progression of malignant hepatic tumours.