FASN and cancer: FASN expression in cancer cells is also activated by activation of tumor suppressor gene downstream pathways, for example, phosphoinositide-3 kinase (PI3K)/v-akt murine thymoma viral oncogene homolog (AKT)/rapamycin complex 1 (mTORC1) and mitogen-activated protein kinase (MAPK) signaling pathways, leading to enhanced tumorigenesis [39, 41].