Figure 1.

A model for MYC-induced differentiation in the chick neural tube: facts and concepts.

(A) Lower levels of MYC, indicated by the smaller symbol, in RGCs promote symmetric planar cell division, whereby active NOTCH signaling maintains the RGC pool.(B) With signaling that promotes neurogenesis, MYC is induced (larger symbol) leading to asymmetric apico-basal cell division. This causes the acquisition of neuronal differentiation features in daughter cells, probably in one of the daughter cells, in association with NOTCH downregulation and inhibition of the NOTCH target genes HES1 and HES5. Dashed arrow indicates the unclear mechanisms of NOTCH inhibition by MYC. Undefined are also the signaling pathways that regulate MYC expression in RGCs and committed progenitors. RGC: radial glial cells.