PTEN and fibrosarcoma: It was discovered that its level in a prostate cancer was raised, showing a pro-oncogenic character; however, in other tumor types (skin tumor, fibrosarcoma, and glioblastoma), EGR1 exhibits features of a tumor suppressor by activating p53 and PTEN to halt the transcription of other genes in the mTOR pathway (Zheng et al., 2009).