RPS6 and medullary thyroid gland carcinoma: Lyra et al. examined mTOR activation in a series of 87 MTCs (10 familial and 77 sporadic) and found RAS mutations significantly associated with a more intense expression of phospho-S6 ribosomal protein (p-S6, a downstream effector of mTOR) [44], pointing to an association between mTOR pathway activation and the presence of RAS mutations in MTC.