To analyze EGF binding activity in liver regeneration at cell cycle level, we performed the double measurement of nuclear DNA content and cellular bound EGF content in freshly isolated rat hepatocytes from normal and regenerating liver after 67% hepatectomy using autostaging cytofluorometry. The data demonstrated that the bound EGF content of resting cells increased in proportion to their DNA content, while cycling cells had significantly consistently lower bound hEGF throughout cell cycle. These changes are supposed to reflect ‘down-regulation’ of EGF receptor at the cell cycle level, and the data suggested a major role of endogenous EGF in cell proliferation during liver regeneration.
