Abstract
Changes in the expression rate of epidermal growth factor receptor (EGFR) mRNA with age in the liver of rats were examined to assess the contribution of EGF to the proliferation of hepatocytes in younger animals. Northern blot analyses with a 32P-labeled probe derived from the extracellular domain of EGFR cDNA were evaluated quantitatively by normalizing the densitometric scanning data with the relative amounts of poly (A) + RNA in the samples. The expression of EGFR mRNA was low during the early period and increased towards the adult level after 21 days of birth. In contrast, the rate of β-actin mRNA expression was significantly higher immediately after birth and showed a tendency to decrease with time.
