PKM and central nervous system cancer: Compared with spheroids that contain rat NSCs, the expression of PKM (analyzed using an antibody that does not discriminate between isoforms 1 and 2) was increased in spheroids that contained CSCs derived from the glioma cell line C6 or from two ethylnitrosourea (ENU)-induced rat gliomas (P7 and M7) obtained as described earlier21 (Figure 1a).