During gastrulation, evolutionarily conserved movements form the germ layers and shape the vertebrate body plan. Previous studies have shown that prostaglandin signalling is required for these gastrulation movements. Now, on p. 1327, Lilianna Solnica-Krezel and colleagues reveal that prostaglandin signalling stimulates gastrulation movements in zebrafish embryos by regulating cell adhesion. Prostaglandin E2 (PGE2), which signals through GPCRs, is synthesized by cycloxoygenase and prostaglandin E synthase. By downregulating these enzymes, the researchers show that strongly reducing PGE2 synthesis impairs all the gastrulation movements in zebrafish embryos in part by increasing cell-cell adhesion. PGE2 signalling normally limits cell adhesion and promotes cell protrusive activity during gastrulation, they report, by modulating E-cadherin transcription, partly through the stabilisation of Snai1a, a transcriptional repressor. Together, these results suggest that ubiquitously expressed PGE2 synthesizing enzymes promote Snai1a stability to allow the precise regulation of cell adhesion that is required for gastrulation movements. In addition, these results provide new clues about how PGs promote cancer cell invasiveness.