PDGFB and glioblastoma: PDGFB-induced glioma primary cultures (PIGPC) and GBM cultures maintained under serum-free conditions (U3046MG, U3035MG, U3082MG, U3084MG, and U3065MG) [23] showed a band pattern similar to murine glioma (Fig. 2a), while serum-cultured cell lines T98G and U251MG showed a single DLK1 band (Fig. 2a).