<i>WRN siRNA</i> knockdown and telomere length of U-2 OS cells.

<p><b>A</b>. U-2 OS cells were mock transfected or transfected with SC or <i>WRN siRNAs</i>. Whole cell extracts were collected, separated by SDS-PAGE and western blotted with antibodies to WRN to confirm the knockdown (top panel), cleaved PARP1 to examine apoptosis induction (middle panel) and lamin B as a loading control (bottom panel). Treatment with camptothecin is a positive control for the induction of apoptosis. <b>B</b>. To inhibit apoptosis, U-2 OS cells were transfected with <i>WRN</i> and <i>p53 siRNAs</i>. Whole cell extracts were separated by SDS-PAGE and western blotted with antibodies specific to WRN (top panel), p53 (middle panel) and lamin B (loading control; bottom panel). <b>C</b>. DNA from transfected U-2 OS cells was collected at 77 PD and telomere length was measured by qRT-PCR. Average relative telomere repeat lengths are graphically represented as the difference between a telomere-specific PCR reaction in comparison to the single copy gene <i>ALB</i> PCR reaction, or delta C_t. (ALT = alternative lengthening of telomeres; PD = population doubling)