Marei et al. (33) have shown that PREX1, but not TIAM1, binds the actin remodeling protein FLII and that this is necessary for Rac-dependent cell migration in NIH3T3 cells; this is a likely candidate for a second PREX1-dependent signaling event that is required for glioblastoma motility. This evidence concerns the gene TIAM1 and glioblastoma.