S6

S6 ribosomal protein was the first S6 kinase substrate identified, and it is one of the ribosomal proteins of the 40S subunit of eukaryotic ribosomes. S6 ribosomal protein is phosphorylated by p70 ribosomal S6 kinase (P70S6K), which is the downstream effector of mammalian target of rapamycin (mTOR). Activation of S6 ribosomal protein is thought to be involved in the regulation of translation.