Fig. 1

a. Characterization of ALT phenotypes in a panel of immortalized cell lines. Real time quantitative TRAP assay to determine the telomerase activity in the indicated cell lines. Histogram represents the fold change of telomerase activity compared to HCT116 sample. b. Dot blot analysis of c-circles in presence or absence of Phi26 DNA Pol enzyme in the indicated cell lines, hybridized with a ³²P radiolabelled telo-probe. c. Densitometry of c-circles signals. For each cell line the background value (-Phi26 DNA Pol sample) was subtracted and reported in histograms. d. Quantitative analysis of the average telomere length in the indicated cell lines. Each sample underwent Southern blot analysis of the Telomere restriction fragments with a ³²P radiolabelled telo-probe. Signals were quantified to determine the average telomere length reported by histograms. e. RNA samples extracted from the indicated cell lines underwent Northern blot analysis. The filter was hybridized with a ³²P radiolabelled telo-probe for TERRA detection and the signals were acquired by Phosphoimager