Migrating cells, it seems, cover their tracks not for fear
of being followed, but to keep moving forward. Scientists at the European
Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, have now shown that
cells in a zebrafish embryo determine which direction they move in by
effectively erasing the path behind them. The findings, published online today
in Nature, could have implications not just for development but also for cancer
and metastasis.