The researchers made great progress in the early 1970s, when they discovered that oncogenes, which are cancer-causing genes, are inactive in normal cells.

研究人员在70年代早期取得了很大进展，他们发现导致癌症的癌基因在正常细胞里是不活跃的。

The identification of these new potential cancer-causing genes is critical to uncovering novel pathways that drive the conversion of a normal cell to a cancerous one.

确定这些潜在导致癌症发生的新基因，对研究正常细胞转化成为癌细胞的新途径来说至关重要。