The PI3k/GSK3β pathway also regulates Notch signalling in CHO cells and in primary neurons. (A) CHO-N2 cells were co-cultured with increasing numbers of either CHO-hDelta1 or control CHO cells and luciferase reporter activity assayed for after 24 hours. CBF1-dependent reporter activity is presented as the fold induction in luminescence versus CHO-N2 cell only value. Mean ± sem given. (B) CHO-N2 cells were co-cultured with 104 CHO-hDelta1 cells per well ± insulin ± LY294002 as indicated. CBF1-reporter activity is presented as fold induction of non-insulin stimulated cells. (C) CHO-N2 cells were co-cultured with increasing numbers of CHO-hDelta1 in the presence or absence of LiCl (10 mM). (D) Rat primary hippocampal neurons were transfected with 0.5 μg of p10xCBF1-luc and 0.05 μg pTK-RL, then stimulated overnight with either LiCl or 25 ng/ml BDNF ± 10 μM LY294002. (E) Neurons were transfected with 0.2 μg of p10xCBF1-luc, 0.05 μg pTK-RL, 0.05 μg of pN1-IC and 0.4 μg of the relevant expression plasmid. CBF1-reporter activity is presented as normalised luminescence ± s.e.m (n = 3).(*p < 0.05, Mann Whitney U test).