To test the in vivo relevance of the tumorsphere experiments, we implanted equal numbers of Bmi1 silenced and control lentiviral transfected CD44+CD24+ESA+ CSCs derived from primary human pancreatic cancer xenografts in the subcutaneum of NOD/SCID mice and measured the resultant tumor growth. This evidence concerns the gene BMI1 and familial pancreatic carcinoma.