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Summary The lower rhombic lip (LRL) is a germinal zone in the dorsal hindbrain productive of tangentially migrating neurons, streaming extramurally (mossy fiber neurons) or intramurally (climbing fiber neurons). Here we show that LRL territory, operationally defined by Wnt1 expression, is parceled into molecular subdomains predictive of cell fate. Progressing dorsoventrally, Lmx1a and Gdf7 expression identifies the primordium for hindbrain choroid plexus epithelial cells; Math1 , for mossy fiber neurons; and immediately ventral to Math1 yet within Wnt1 + territory, a climbing fiber primordium dominated by Ngn1 -expressing cells. Elimination of Pax6 results in expansion of this Ngn1 + progenitor pool and reduction in the Math1 + pool, with accompanying later enlargement of the climbing fiber nucleus and reductions in mossy fiber nuclei. Pax6 loss also disrupts Msx expression cell-nonautonomously, suggesting Pax6 may influence LRL progenitor identity indirectly through potentiating BMP signaling. These studies suggest that underlying the diversity and proportions of fates produced by the LRL is a precise suborganization regulated by Pax6.

from endogenous locus. Viral cre delivery via adenoviral or lentiviral inoculation (intranasal or intratracheal).Adenocarcinoma spectrum histology (i.e., in situ and invasive neoplasia) in lung; metastasis not reported.K-ras somatic mutations identified in ~20%-30% of lung adenocarcinomas. Mouse models of the oncogenic K-ras allele have been used in preclinical studies of cisplatin resistance and combination targeted therapies.K-ras