Expression analysis by qPCR, using human-specific primers, showed a significant increase in the expression of some chemoattractant factors (i.e., CCL2 and CSF1) of the cell-cycle inhibitor P21 in the tumor cells of PTP4A2-KO xenografts (Fig. 4; Supplementary Fig. S6A and S6C). This evidence concerns the gene CCL2 and neoplasm.