FIG. 1.

(A) Cellular fractionation of HeLa cells infected with wild-type EPEC. Samples were derived from the pellet (lane 1) or supernatant (lane 2) of the medium obtained from HeLa cells infected with EPEC, from the lysate of the infected HeLa cells (lane 3), or from the pellet of lysed infected cells (lane 4). Equivalent volumes of these samples were separated by SDS-polyacrylamide gel electrophoresis, transferred to membranes, and probed with a monoclonal antibody to phospholipase C-γ (PLC-γ), a monoclonal antibody to the human fibronectin receptor, or a polyclonal antibody to the EPEC adhesin intimin. (B) Detection of EspB in fractions from infected HeLa cells. HeLa cell fractions, as defined for panel A, were separated by SDS-polyacrylamide gel electrophoresis, transferred to membranes, and probed with an affinity-purified anti-EspB antibody. Samples were prepared from HeLa cells infected with wild-type EPEC E2348/69, with the wild-type strain in the presence of cytochalasin D (cyto-D) or genistein, and with espB mutant strain UMD864, as indicated.