Unlike in a previous report16, the present study showed that the deacetylation mimetic HINT1 mutant (at both K21R and K30R) inhibits cell proliferation in DLD1 colon cancer cell lines and A375 melanoma cell lines, although the study did not include a soft agar assay; the findings indicate that reversible acetylation of HINT1 at both K21 and K30 might have an important role in cell proliferation. This evidence concerns the gene HINT1 and melanoma.