High prevalence of BRAF mutations in thyroid cancer: genetic evidence for constitutive activation of the RET/PTC-RAS-BRAF signaling pathway in papillary thyroid carcinoma - Kimura, E T; Nikiforova, M N; Zhu, Z; Knauf, J A; Nikiforov, Y E; Fagin, J A (Cancer Res, 2003)