CDKN1B and Global developmental delay: In the TAG/F3 model, previous studies demonstrated that Contactin1 overexpression correlates with a Notch pathway activation, with a concomitant decreased expression of cell cycle exit (p27Kip1) and neuronal commitment and increased expression of proliferation (BrdU) markers (Bizzoca et al., 2012), thus justifying positive Contactin1 effects on precursor proliferation and negative effects on cell cycle exit and neuronal commitment, which resulted into a developmental delay.