PML and central nervous system cancer: MGG119 and SF8628 are adult and pediatric glioma cell lines, respectively and both display the characteristics of ALT-dependency as demonstrated increased telomeric sister-chromatid exchange (T-SCE) (Figures 1B, C), increased ALT-associated PML nuclear body (APBs) formation (Figures 1B, D) and presence of c-circle DNA (Figure 1E), relative to non-ALT MGG152 adult glioma cells) (11, 13, 14, 16, 17).