Table 1. Statistical analysis of cytogenetic abnormalities.

Comparison group	Comparison values	P value
No. of fragments per metaphase
WT hTERT vs. vector control	0.524 vs. 0.718	0.41
Vector control vs. hTERT shRNA	0.718 vs. 1.31	0.02
WT hTERT vs. hTERT shRNA	0.524 vs. 1.31	0.008
Proportion of normal metaphases
WT hTERT vs. vector control	0.619 vs. 0.462	0.25
Vector control vs. hTERT shRNA	0.462 vs. 0.241	0.058
WT hTERT vs. hTERT shRNA	0.619 vs. 0.241	0.008

Metaphase chromosomes were examined at 24 h after exposure to ionizing radiation (5 Gy) from BJ cells expressing a control vector, an hTERT-specific shRNA, or WT hTERT. P values were obtained by applying the Wilcoxon rank-sum test. Comparison values were calculated by dividing the number of the indicated findings by the number of metaphases examined. We also observed that total number of cytogenetic abnormalities found in hTERT shRNA-expressing cells was slightly increased when compared with vector control cells (P = 0.09). The number of metaphase cells examined was as follows: cells expressing WT hTERT (21 cells), cells expressing the hTERT-specific shRNA (29 cells), and cells expressing a control vector (40 cells). Examination of metaphases from unirradiated cells expressing the control shRNA (13 metaphases) or the hTERT-specific shRNA (15 metaphases) revealed no fragments.