NOTCH1 and neoplasm: Moreover, Notch 1 and Notch 2 appear to have opposite functions in embryonic brain tumors (Fan et al., 2004) and pancreatic ductal adenocarcinoma (PADC) (Hanlon et al., 2010; Mazur et al., 2010), adding another layer of complexity on the role of Notch signaling in tumor progression.