PTHrP, also named parathyroid hormone-related protein, is belonging to the parathyroid hormone family. PTHrP is expressed in cancer cells (breast cancer, certain types of lung cancer including squamous cell lung carcinoma). The receptor for PTHrP is PTHR1. PTHrP plays a central role in regulating the hypercalcemia. Recombinant human PTHrP is a 9.9 kDa linear polypeptide of 86 amino acid residues and it shares 86 % a.a. identity with mouse PTHLH.