RET and medullary thyroid gland carcinoma: The biological effects of the NDI derivative (Figure 1A) were investigated in two human MTC cell lines, namely TT cells harboring both a MEN2A-type C634W RET mutation and a tandem duplication of the mutated RET allele [19] and MZ CRC-1 cells harboring the M918T RET mutation found in about 50 % of sporadic MTC and the most common RET mutation in the MEN2B syndrome, associated with an aggressive disease behavior [19].