MKI67 and cancer: While the proliferative rate of the two adhering cell types, evaluated as the percentage of the cells positive for the Ki67 nuclear signal was comparable (21% ±2 and 23% ±2 for the Caco2 and AGS cells respectively; Kruskal-Wallis test: p  = NS), their distribution revealed a different behaviour of the cancer cells (Fig. 1D).