PIK3CA and thyroid cancer, nonmedullary, 2: Moreover, in FTC, some more mutations in genes have been observed, although they are not so frequent, namely PI3CA, PTEN, DICER1, EZH1, and SPOP [52], some of which are engaged in the PI3K/PTEN/AKT pathway, which has been found to be a key signaling pathway in FTC development [53].