For example ZO-1 which is required for the RhoA GEF ARHGEF11 and Cdc42 GEF Tuba to localize and function at TJ (Table 1 and Fig. 2a and b) relocalizes from TJs in several breast cancer cell-lines and regulates CXCL8/IL-8 expression, a protein strongly implicated in tumour invasion (Brysse et al., 2011). Here, CXCL8 is linked to breast cancer.