High PTH levels may be caused by: 1  A parathyroid gland growth (hyperplasia) or a parathyroid tumor. 2  A low level of calcium in the blood. 3  Some types of cancer, such as of the lung, kidney, pancreatic, or ovarian cancer.
MTOR inhibitors What are MTOR inhibitors. Mammalian target of rapamycin (mTOR) inhibitors block the activity of the mammalian target of rapamycin. Mammalian target of rapamycin is a protein kinase, which regulates growth factors that stimulate cell growth and angiogenesis. In certain cancers the mTOR pathway is more active. Mammalian target of rapamycin (mTOR) inhibitors are used in treatment of renal cancer and is being studied for use in other types of cancers.
Receptor tyrosine kinases (RTKs), which bind to peptide / protein hormones, may exist as dimers or dimerize during binding to ligands. Ligand binding leads to activation of the kinase activity of the receptor and autophosphorylation of tyrosine residues in its cytosolic domain (see Figure 20-31).The activated receptor also can phosphorylate other protein substrates.igand binding leads to activation of the kinase activity of the receptor and autophosphorylation of tyrosine residues in its cytosolic domain (see Figure 20-31). The activated receptor also can phosphorylate other protein substrates.