To investigate whether SA-β-gal-positive tumor cells in our samples were growth arrested, we analyzed the expression of the proliferation marker Ki67 as well as additional proteins that are inhibitors of cell cycle progression such as p53, p16INK4A, and p21Cip1/Waf1 within SA-β-gal positive tumor cells as described previously [38]. Here, CDKN2A is linked to neoplasm.