Given that the basal expression of PDGFRβ and c-KIT was not detectable in HepG2 cells both in our and previous reports and the relationship between CSF1R and HCC was rarely reported15,16, we speculated that these protein kinases might play negligible roles in the regulation of cellular signaling mediated by E5. The gene discussed is CSF1R; the disease is hepatocellular carcinoma.