SIX3 and glioblastoma: Using methylation-specific PCR (MSP) primers (Fig. S1B), we detected SIX3 DNA methylation in the phenotypically normal astrocyte cell line HEB and three glioblastoma cell lines (U251, U87, and U118), and the level of methylation correlated inversely with the expression of SIX3 (Fig. S1C, D).