MKI67 and urinary bladder neoplasm: Co-incubation of CD45+ cells isolated from MB49luc bladder tumors of control Ig–treated mice with either CD4+ or CD8+ T cells from naïve mice (ratios of 1:2 and 1:4) significantly reduced the percentage of CD4+ or CD8+ T cells expressing Ki67 (Fig. 4b, c).