Notably, the increased cell motility of ASS1-KO HEC1B cells was not observed when these cells underwent starvation and then were re-supplemented with lysine, which is a cationic amino acid like arginine and also an essential amino acid (see Supplementary Fig. S6(a) and S6(b)), suggesting that the specific activity of arginine affects tumor cell motility and invasion capability. Here, ASS1 is linked to neoplasm.