ＳＭＭＣ－７７２１人肝癌细胞株经β－胡萝卜素（４６．５－μｍｏｌ／Ｌ）体外作用９６小时后，采用流式细胞仪分析该株癌细胞的生长周期，并对细胞的总ＲＮＡ分别作ＮｏｒｔｈｅｒｎＢｌｏｔ及ＤｏｔＢｌｏｔ以定性、定量分析Ｎ－ｒａｓ基因的表达水平。结果为β－胡萝卜素处理之细胞Ｓ期百分率仅为１７％，而对照组Ｓ期百分率为２７％，以及Ｎ－ｒａｓｍＲＮＡ表达水也受到明显的抑制，比对照组抑制１２０倍左右。上述结果表明β－胡萝卜素除能在体外阻断肝癌细胞株生长周期外，还能明显地抑制Ｎ－ｒａｓ基因的表达。 After SMMC-7721 human hepatoma cell line was treated with β-carotene (46.5-μmol/L) for 96 hours in vitro, the growth cycle of the cancer cell was analyzed by flow cytometry, and the total RNA of the cell was made NorthernBlot, respectively. And DotBlot qualitatively and quantitatively analyzed the expression level of N-ras gene. As a result, the percentage of S-phase cells treated with β-carotene was only 17%, while the percentage of S-phase in the control group was 27%, and the water of N-ras mRNA expression was also significantly inhibited, which was about 120-fold suppressed compared with the control group. The above results indicate that β-carotene can significantly inhibit the expression of N-ras gene in addition to blocking the growth cycle of hepatoma cell lines in vitro.