Taken together, all these findings may indicate that the extent of PDGFβR activation may correlate with E5 expression levels and the number of viral copies; direct association of viral load with impaired expression of tyrosine kinase receptors has been reported for human cervical tumours harboring human papillomavirus, suggesting that the impairing of these cellular functions may depend on the viral load in PVs induced cancer [57]. This evidence concerns the gene ARHGEF15 and cancer.