Consistent with reduced proliferation being a factor in the LSL-K-RasG12D;K14-Cre:ER; Rac1Wt/- mice, Ki-67 staining in tumours was markedly reduced compared to those observed from LSL-K-RasG12D;K14-Cre:ER mice (Figure 2C). This evidence concerns the gene MKI67 and neoplasm.