The movie shows a segment of the mutant intestine (3.5 day old fish, lateral view of the intestine). The time lapse images were taken over about six to eight hours. It is a transgenic mutant zebrafish that expressed the green fluorescent protein tagged to a peptide that binds to actin in epithelial cells. Normally actin lines the portion of the intestinal cells that are adjacent to the lumen of the intestinal tube. This is the bright green staining in the intestine. In the mutants, there also are small actin rich protrusions that appear within the plasma cell membrane on opposite side of the cells undergoing invasion. Invasive cells with these protrusions expand out in to the surrounding tissue stroma (arrows). The green structure on the top of the movie frame is the kidney duct. The intestine is below the kidney duct. The actin-rich protrusions are the invadopodia. Transcriptome profiles of the cells with invadopodia showed that genes responsive to reactive oxygen species were upregulated in young mutant fish.