Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase and has been known to play its role in cell growth and proliferation. mTOR is activated by phosphorylationin response to growth factors, mitogens and hormones. Rapamycin is a macrolide antibiotic from Streptomyces hygroscopicus that specifically inhibit the activity of mTOR.