CXCR4 and cancer: The proportion of suspected cancer stem cell population (CD133+CXCR4+ and CD133+CXCR4−) was found to be higher in primary cells established from type II endometrial tumour sample (5.7% and 74%) as compared to primary cells established from type I endometrial tumour sample (1.4% and 33%) (Fig. 2C).