Gene regulation by transcriptional and post-translational mechanisms is implicated in the regulation of cellular homeostasis. Transcriptional deregulation has been largely documented in the etiology of diseases such as cancer, obesity and diabetes. During the past decade, the control of translation initiation by the PI3K/Akt/mTOR pathway in the development of these pathologies has been documented. Rapamycin, a specific inhibitor of mTOR, demonstrates considerable anti-proliferative activity against numerous cancer types. Recent studies also demonstrated that rapamycin may be beneficial in the treatment of obesity and diabetes. Rapamycin and its analogs seem destined for a promising future and will help in the development of novel therapeutic strategies.