Expression of c‐raf‐1 and A‐raf‐1 during regeneration of rat liver following surgical partial hepatectomy

The major objective of this study was to investigate the expression of members of the raf family of protooncogenes during rat liver regeneration. The steady‐state level of expression of both c‐raf‐1 and A‐raf‐1 increased three‐ to fivefold 18–24 h following partial hepatectomy, and it returned to basal levels by 72 h. Expression of c‐myc and Ha‐ras mRNA was increased at 3 and 18–24 h, respectively, confirming previous reports. Increased steady‐state levels of c‐raf‐1, A‐raf‐1, and Ha‐ras mRNA were also detected in hepatocytes isolated from rat liver 24 h after partial hepatectomy. Thus, elevated expression of the raf genes closely correlated with that of Ha‐ras, beginning at 12 h and reaching maximal levels during the first peak of DNA synthesis following partial hepatectomy.