In most motile immune cells, cathD is constantly expressed at high levels.12,13 Increased cathD level enhances the proliferation and invasion of cancer cells, which is positively correlated with poor prognosis.14–16 We recently found that cathD interacted with the actin-severing factor cofilin and regulated actin-based fast cell migration after translocation to cytosol.17 Intriguingly, although cofilin is widely expressed, only two specific cofilin phosphatases, chronophin (CIN) and slingshot (ssh), have been identified so far. This evidence concerns the gene CFL1 and cancer.