Telomere lengths of hTERT-expressing normal and G6PD-deficient fibroblasts. Cells were cultivated successively by 1:8 spliting in each passage. The telomere lengths of hTERT-expressing normal fibroblasts (Panel A) and G6PD-deficient fibroblasts (Panel B) at different passages were determined as described in M & M. Lanes S and L are controls supplied with the assay kit for DNAs having short or long TRF lengths, respectively. Lane P is the DNA from the parental cells before transfection. The mean telomere restriction fragment (TRF) lengths in kilobases (kb) are indicated below each lane. Molecular weight (M.W.) markers ranging from 1.6 to 21.2 kb are marked at the left.