CDC42 and cancer: Cdc42 and MT1-MMP, increased by the downstream effects of intracellular pathogens on human host cells (see above steps), are critical for invasion of many cancer types [27] but also cdc42 may be linked with formation of tunnelling nanotubes which may enable further cell to cell spread of invasive intracellular bacteria (Fig. 1) [20,133, 135].