To further examine the involvement of the ERK1/2 signaling pathway on tumor growth, stemness, and invasiveness in vivo, we created flank tumor xenografts using 5000 CD44(+)-SCC-25 cells transduced with sh.ERK1/2 or sh.Scr and injected them into the immunodeficient mice; knockdown was confirmed by western blot (Suppl. Here, CD44 is linked to neoplasm.