NLK and medulloblastoma: An intriguing observation concerns the fact that three genes in Set A whose expression is significantly modified - namely, Nlk, Raf1, and Ppp2r2b—are markers for group 3 medulloblastoma (Kool et al., 2008; Gibson et al., 2010; Northcott et al., 2011, 2012c; Taylor et al., 2012; Hooper et al., 2014).