S6K

S6K is a serine/threonine kinase that is a member of the ribosomal S6 kinase (RSK) family. S6K exists in two main isoforms, S6K1 and S6K2, which can also be alternatively spliced to produce different splice forms. S6K1 has two major splicing products that are approximately 70 kDa and 85 kDa, known as p70S6K and p85S6K respectively. S6K is activated via phosphorylation by mTORC1 which relieves the autoinhibition of S6K. Active S6K phosphorylates the ribosomal S6 protein, which induces protein synthesis and cell growth and proliferation.

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.