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作者用低剂量γ射线预照射同源但辐射敏感性不同的小鼠乳癌细胞ＳＫ－１和ＳＸ－９，观察其对随后较大剂量照射所引起ｈｐｒｔ基因突变的影响．结果，具有辐射抗性的ＳＲ－１细胞经５ｍＧｙ或１ｃＧｙ低剂量顶照射后，能显著降低随后３Ｇｙ照射诱发的ｈｐｒｔ基因突变频率．而ＤＮＡ双链断裂修复能力缺陷的电离辐射敏感细胞ＳＸ－９，经相同处理后，并不减轻随后的较大剂量照射所诱发的基因突变率．表明ＤＮＡ双链断裂修复缺陷的细胞，对低剂量辐射诱导的适应性反应能力差．
The authors preliminarily irradiated homologous but differentially expressed mouse breast cancer cells SK-1 and SX-9 with low-dose γ-rays and observed their effect on subsequent hprt gene mutation induced by higher dose radiation. As a result, radiation-resistant SR-1 cells significantly reduced the frequency of hprt gene mutations induced by subsequent 3Gy irradiation after 5 mGy or 1 cGy low dose top irradiation. However, SX-9, an ionizing radiation-sensitive cell deficient in DNA double-strand break repair ability, did not reduce the gene mutation rate induced by the subsequent larger dose irradiation after the same treatment. Cells showing defects in repair of DNA double-strand breaks were poorly responsive to low-dose radiation-induced adaptive responses.