Figure 5: summarizes the mechanism of cisplatin resistance from our studies: cisplatin activates the DNA damage repair pathway, with marked Chk2 phosphorylation and ERCC1 overexpression. Chk2, the upstream regulator, is modulated by p53. Within the process of cisplatin-induced cell cycle arrest, DNA-adduct repair protein ERCC1 increases and contributes to the increase of cisplatin resistance. Two transcriptional factors AP1 and MZF1 can modulate the ERCC1 expression [42].