To examine whether plexin-A1 konckdown affects tumor formation in vivo, we subcutaneously inoculated shNC MGC803 cells (Fig. 11a), shPlexin-A1 MGC803 cells (Fig. 11c) or RPMI-1640 medium (blank control group, Fig. 11b) into BALB/c nude mice. This evidence concerns the gene PLXNA1 and neoplasm.