RET and thyroid gland undifferentiated (anaplastic) carcinoma: Intriguingly, in the human anaplastic thyroid cancer line ARO, STAT3 could directly interact with ectopically expressed RET/PTC1 and phosphorylation of its Tyr705 did not require either JAK or c-Src kinase, indicating a possibility of direct STAT3 activation by the oncogenic kinase [98].