A splendid clonal-lineage tracing study (with 9 reporter mice!)->
A very early time window e11.5-13.5 for lineage specification of mouse Lung Nkx2-1+ Alveolar epithelial progenitor

Dr. David Frank, Rajan Jain & Edward E. Morrisey labs, PNAS 2019
https://www.pnas.org/doi/10.1073/pnas.1813952116