PPM1D and carcinoma: In addition to the important function of Wip1 in the DDR, Wip1 has been identified as an oncogene because Wip1 overexpression or PPM1D amplification is found in many types of carcinomas, such as breast [7], gastric [8], and lung [9] carcinomas, and high expression of Wip1 may cause tumorigenesis by suppressing the function of the tumour suppressor p53.