Supplementary Movie 2

Time-lapse imaging of Hoxb7^Cre/+;mTmG;Hnf1b^fl/LacZ kidney shows defective branching pattern. Tip domain show active cell movements but lumen in the trunk is barely visible. By the end of the movie, WT cells appear to be recruited at the UB tip domain and correctly formed nascent nephrons are observed. One image is taken every 10 minutes. Green is mG expression in Cre expressing cells. Red is mT expression in Cre-non expressing cells. Mitotic cells can be easily detected as they become round before division.