To discern the underlying signalling responsible for the different roles of KRas and HRas in mediating the pro-bone metastasis of MAZ overexpression in PCa, the effects of KRas and HRas on the expression levels of p-Erk, p-AKT and activated RalA were further investigated by constructing KRas or HRas expressing PCa cell lines by ectopically overexpressing KRas or HRas in PC-3 cells and endogenously knocking down KRas or HRas by retrovirus infection in PC-3 and VCaP cell lines (Additional file 5: Figure S5A-C). This evidence concerns the gene KRAS and posterior cortical atrophy.