VCL and infection: Moreover, barcoded infections reveal that a minimal set of T3SS effectors required for early Shigella colonization of a nontransformed human intestinal epithelium includes four main effectors: IpgB1 and IpgB2 (Rho GTPase GEFs; see refs. 48–50), IpaA (a vinculin-binding and actin-depolymerizing protein; see refs. 51,52) and VirA (a Rab GAP; see refs. 53,54).