Correlation between ALT activity and lack of normal ATRX expression.

a6/7 ALT hybrids underwent a period of growth arrest compared to 3/12 TEL hybrids (p = 0.0198, Fisher’s exact test);bTRAP assay: “+” indicates detectable telomerase activity (Figure 2);cTRF: “+” indicates a terminal restriction fragment length pattern characteristic of ALT (Figure 3);dCC assay: “+” indicates C-circle levels above the cut-off level for ALT activity (Figure 4);eTLM: telomere lengthening mechanism deduced from TRAP, TRF and CC assay data; ALT and TEL indicate ALT-positive and telomerase-positive, respectively;fATRX protein: “+:” indicates normal pattern of immunofluorescence (Figure 5) and normal levels on Western (Figure 6);gATRX SNP: a single nucleotide polymorphism (rs3088074, c.3017C>G, p.Q929E) for which each of the parental lines is homozygous identified the parental origin(s) of the ATRX alleles in all hybrids except the TE-85/GM847 lines for which the SNP was not determined (nd), because TE-85 and GM847 both have G at this location;hThe magnitude of the C peak was significantly smaller than that of the G peak;iATRX exon 1: “+” indicates the presence of wild-type ATRX exon 1 as determined by PCR (Figure 7).