TP53 and central nervous system cancer: p53 was expressed in 2 out of 9 cases (22.2%) of grade I gliomas, 40 out of 56 cases (71.4%) of grade II gliomas, 38 out of 52 cases (73.1%) of grade III gliomas and 21 out of 35 cases (60.0%) of grade IV gliomas.