CALCA and medullary thyroid gland carcinoma: The MTC-derived cell line TT transfected with pGL3-pC/CGRP yielded a RFLA (19.5% +/- 7.5 of Renilla luciferase activity), which was significantly (pc < 0.05) higher than nine non-MTC cell lines tested, including cell lines derived from human follicular thyroid tissue, K1 (2.48% +/- 0.78) and Nthy-ori-3.1 (1.4% +/- 1.95) (Fig 2A).