The role of plexin-B2 as a target for Rnd3 signalling could explain the apparently opposing effects of plexin-B2 in cancer cell invasion and cancer progression: in some cancer types such as breast cancer, both Rnd3 and plexin-B2 appear to inhibit hallmarks of tumorigenesis (Malik et al., 2015; Zhu et al., 2014), whereas in gliomas they promote tumour progression (Clarke et al., 2015; Le et al., 2015). This evidence concerns the gene PLXNB2 and breast carcinoma.