Reelin treatment activates Notch-1. A, HNPCs were treated with partially purified control or Reelin with and without γ-secretase inhibition for 24 hours before analysis. Reelin addition in vitro increased the accumulation of NICD by 1.7 fold in the treated HNPCs, * p-value = 0.05, where γ-secretase inhibition abolished this increase, ** p-value = 0.05. The results represent the standard error of the mean ± SEM of at least three independent experiments. One-way ANOVA with Tukey's post hoc test for individual treatment differences was used for statistical analysis. Values that are significantly different from each other according to Tukey's test are indicated by asterisks B, Western blots showing reciprocal co-immunoprecipitation (IP). HNPCs were transfected with Dab-1 with a flag tag added to its C terminus for 24 hours before cell lysis. a, Co-immunoprecipitation of Notch-1 by Dab-1. b, Co-immunoprecipitation of Dab-1 by Notch-1. c, Co-immunoprecipitation of Dab-1 by NICD. d, Co-immunoprecipitation of NICD by Dab-1. Anti-Flag was used to immunoprecipitate Dab-1 from the cell lysate.