Effects of high-dose BIBR1532 on human fibroblast cells (HK1). Proliferation of HK1 fibroblasts upon exposure of indicated concentrations of BIBR1532. (A) Wild-type HK1 cells. (B) HK1 cells expressing ectopic hTERT. The red arrow and label on the x-axis indicate the time point of cell death. Summary of corresponding telomere length values of wild-type HK1 and HK1-hTERT is presented in Tables 5 and 6, respectively.