Table 3. Telomeric recombination induced by aphidicoline.

Cell clone	Frequency of recombination	− APC	+ APC	− TmPy	+ TmPy
SW 26 subtel-15/tel-4	mean	2,6	4,8	1,9	7,6
	low recombination (≤ 3,9)	2,5	4
	high recombination (> 3,9)	57,5	107
+hTERT pool	mean	0,3	0,3
+ hTERT clone 3	mean	0,2	0,2
+ hTERT clone 4	mean	0,3	0,3
SW 26 subtel-15/tel-2	mean	2,6	6,0
SW 39 subtel-17/tel-12	mean	4,3	4,4	1,6	10,1
SW 39 subtel-17/tel-17	mean	2,6	2,9

Telomeric recombination in SW 26 and SW 39 cells exposed to aphidicoline and TmPy4 (expressed as number of colonies/1 × 10⁷ cells). Aphidicoline lead to a moderate but consistent increase in the frequency of homologous inter-telomeric recombination in two ALT cell clones. This increase was observe in cells that were in a lower state of recombination (cut off 1.5-fold of the mean frequency of recombination) as well as in cells that were at a recombinogenic peak. Reconstitution of telomerase activity in SW 26 cells abolished APC induced recombination. In addition no increase in recombination with APC was seen SW 39 cell clones. The G4 DNA stabilizing substance TmPy4 however increased the frequency of inter-telomeric recombination in SW 26 and SW 39 cells.