In tumor cells, caffeine could lead to selective radiosensitization of p53-deficiency cells through activating the p34cdc2 kinase [38] and the radiosensitizing effects of the caffeine were also related to its inhibitory activities on the catalytic activity of both ATM and the related kinase, ATM and Rad3-related (ATR) [39]. Here, TP53 is linked to neoplasm.