PTEN and leukemia: In leukemia, 80S ribosomes occur at the crossroads of at least two important transformation pathways: the mTORC1 which acts downstream of the PTEN-PI3K-Akt axis to stimulate translation initiation, and the c-MYC proto-oncogene, frequently amplified in cancer/leukemia, which acts by stimulating many molecular steps of PS and increasing the number of ribosomes (see below).