RHOA and neoplasm: Indeed, a siRNA dose dependent decrease of p190RhoGAP expression in SCC A431 cells (Supplementary Figs. 7a and  14a) resulted in a siRNA dose-dependent increase of RhoA-GTP levels (Supplementary Figs. 7b and 14b) and a similar decrease of ATX expression levels (Supplementary Fig. 7c and 14c), indicating that the increased RhoA activity into tumour cells contributes to reduced ATX expression detected on tumour sections (Fig. 6 and Supplementary Fig. 6).