XPA and neoplasm: Consistent with our XPA-MK2 findings in human fibroblasts, knockdown of XPA using siRNA in murine KP7B lung adenocarcinoma cells resulted in a similar increase in both p38 and MK2 at 6 h after treatment with cisplatin, indicating enhanced reliance on MK2 signaling in these tumor cells when the NER pathway was impaired (Fig. 1d).