video) don’t move around much an appear to be ‘frozen’ in place. Such mice die within the first three weeks after birth (see Table 1). Found at: doi:10.1371/journal.pgen.1000878.s017 (3.20 MB AVI) Video S3 Wild-type cells moving into the wound cover the entire wound area over 12 hours. Found at: doi:10.1371/journal.pgen.1000878.s018 (2.69 MB AVI) Video S4 Ate1 knockout cells moving into the wound are significantly slowed down and do not cover large areas over extended periods of time. Found at: doi:10.1371/journal.pgen.1000878.s019 (2.70 MB AVI) Video S5 Ate1 knockout cells (red) co-cultured with wild-type are able to cover larger distances than when migrating by themselves. Some knockout cells could be clearly seen ‘riding’ on the migrating wild-type cells rather than moving on their own. Found at: doi:10.1371/journal.pgen.1000878.s020 (1.78 MB AVI) References 1. Bronner-Fraser M, Fraser SE (1991) Cell lineage analysis of the avian neural crest. Development Suppl 2: 17–22. 2. 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