In the April 5th online edition of Stem Cells, scientists from Cedars-Sinai Medical Center in Los Angeles, A. J. Ghods et al., published the results of their study on using a rat gliosarcoma cell line, 9L, to isolate and characterize a subpopulation of cancer stem-like cells (CSLCs) which were tumorigenic. In the study, the researchers found that the CSLCs formed clonal derived spheres when grown in a serum-free medium supplemented with mitogens EGF and bFGF. The cells derived from the spheres were able to self-renew, express the neural stem cell markers Nestin and Sox2, and differentiate into neurons and glial cells in vitro. Tumorigenicity was confirmed by implanting the cells from the spheres into the brains of syngeneic Fisher rats. The implanted cells displayed an aggressive form of the tumors. In contrast, 9L gliosarcoma cells grown as monolayer cultures were not able to recapitulate the tumor in vivo as the cells from the floating spheres. The investigators further confirmed that the spheroid-derived cells were more chemoresistant and expressed several anti-apoptotic and drug resistant genes than the cells from the monolayer cultures.