BMI1 and brain neoplasm: However, Hemmati et al. examined mRNA expression profiles of differentiated and undifferentiated spheres from six different brain tumours and found higher levels of musashi-1, Sox2, MELK, PSP, Bmi-1, and Nestin were not strictly associated with the undifferentiated spheres but differed strongly among the different specimens and these genes were sometimes even stronger expressed in the differentiated [4].