Figure 1.

Clonogenic survival curves. FaDu^CD44low, SQ20B^CD44low, FaDu-CSCs and SQ20B-CSCs were exposed to photons (A) or carbon ion (B) irradiation in normoxic conditions (21% O₂) or chronic hypoxia (1% O₂). Values represent the mean±s.d. of three (A) or two (B) independent experiments performed in sextuplicate. Student’s t-test was performed between survival fractions of normoxia and hypoxia curves for each cell lines (*P<0.05, **P<0.01 and ***P<0.005).