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ｒａｓ基因家族由Ｈ－ｒａｓ，Ｋ－ｒａｓ和Ｎ－ｒａｓ组成，其表达产物为Ｐ２１蛋白。ｒａｓ基因主要通过点突变激活，其突变位点是密码子１２、１３和６１。肺癌中ｒａｓ基因点突变绝大多数发生在肺腺癌，与吸烟有一定的关系。主要是Ｋ－ｒａｓ基因第１２密码子的点突点。Ｇ→Ｔ突变常见，导致甘氨酸被缬氨酸所代替。有Ｋ－ｒａｓ基因点突变的肺腺癌分化差，患者预后也差。Ｐ２１蛋白在肺癌中的表达一般随着分化的升高而升高。Ｐ２１蛋白阳性比阴性者预后差，有人认为它是一个独立的预后因素。
The ras gene family consists of H-ras, K-ras and N-ras, and its expression product is P21 protein. The ras gene is mainly activated by point mutations and its mutation sites are codons 12, 13 and 61. The majority of ras gene point mutations in lung cancer occur in lung adenocarcinoma and have a certain relationship with smoking. Primarily, it is the point at the codon 12 of the K-ras gene. The G→T mutation is common and causes glycine to be replaced by proline. Lung adenocarcinomas with K-ras point mutations are poorly differentiated and their prognosis is poor. The expression of P21 protein in lung cancer generally increases with increasing differentiation. The positive result of P21 protein is worse than that of negative, and some people think it is an independent prognostic factor.