Activation of the RAF/RAS signal transduction cascade by RAS mutations in serrated neoplasia is mainly observed in hyperplastic (serrated) polyps, and their occurrence in traditional type serrated adenoma is limited, indicating that activation of the RAS/RAF/MEK/ERK/MAP kinase pathway constitutes a highly significant event in the pathogenesis of this group of lesions especially in the early steps in the initiation of the serrated neoplasia pathway [94, 101, 102]. The gene discussed is RAF1; the disease is polyp.