Three kinds of PTC cells lines TPC-1, BCPAP and K1 (identified with RET mutations and BRAF mutation, RET gene rearrangements (RET/PTCs) represent together with BRAF pointmutations the two major groups of mutations involved in papillary thyroid carcinoma (PTC) initiation and progression 16), whose response to TNF-α were similar, suggesting that proto-oncogene mutation in PTC cells did not affect the changes of E-cadherin expression levels. This evidence concerns the gene RET and differentiated thyroid carcinoma.