Table 1. Cell culture growth and expanded CAG·CTG repeat dynamics.

Treatment [drug concentration]	Time [days]	PDs	PDT [h]	BrdU incorporation [%] (P)a	Median repeat gain relative to progenitor [repeats] (P)b	Median rate of expansion [repeats per day] (P)c
Control 1d	121	120	24.2	94	65 (<0.0001)	0.54
Mitomycin C [30 μM]e	54	<1	>3000	6 (<0.0001)	68 (<0.0001)	1.26 (0.005)
Apicidin [320 nM in 0.1% DMSO]	85	<1	>3000	2 (<0.0001)	39 (<0.003)	0.46 (0.066)
Trichostatin A [160 nM in 0.1% DMSO]	120	<1	>3000	0 (<0.0001)	68 (<0.0001)	0.56 (0.81)
Hydroxyurea [50 μM]	121	∼1	∼3000	91 (<0.21)	55 (<0.0001)	0.45 (0.02)
Control 2d	89	100	21.4	94	42 (<0.018)	0.48
DMSO [0.1%]	89	95	22.5	N/D	37 (<0.0004)	0.41 (0.47)
Roscovitine [20 μM in 0.1% DMSO]	89	<1	>3000	26 (<0.0001)	27 (<0.016)	0.33 (0.30)
pSwitch control	89	69	31.0	N/D	45 (<0.0007)	0.50
pSwitch mifepristone A [10 nM]	89	68	31.4	97	92 (<0.0001)	1.04 (0.005)
p16 control	89	74	28.9	N/D	46 (<0.032)	0.52 (0.94)
p16 mifepristone A [10 nM]	89	∼2	∼1000	45 (<0.0001)	83 (<0.0001)	0.93 (0.008)(0.39)f
p21 control	89	69	31.0	N/D	45 (<0.0007)	0.51 (0.69)
p21 mifepristone A [10 nM]	89	<2	>1000	52 (<0.0001)	69 (<0.0055)	0.77 (0.38)

^aEach treatment sample was compared to the relevant control sample using a one-tailed Fisher's exact test.

^bRepeat length distributions in each replicate were compared to the progenitor culture using a one-tailed Mann–Whitney U test. The maximum P-value obtained across all the replicates for each treatment is shown.

^cMedian repeat lengths for each treatment were compared to the relevant control culture using a two-tailed Mann–Whitney U test as previously described (31).

^dChemical cell cycle arrest of cells was performed in two independent experiments, one for MMC, apicidin, TSA and HU treatment, and one for roscovitine treatment.

^eSingle acute exposure.

^fCompared relative to the pSwitch mifepristone A control.