Figure 5.

Exogenously added Hsp70 protein reduces clonogenic cell survival of normoxic, hypoxic, and irradiated CX− tumor cells. A, B) CX− tumor cells were seeded in 3 ml of medium in 6-well plates and incubated with Hsp70 protein (solid circles) or BSA (open squares) at 10 μg/ml (n=7), 25 μg/ml (n=4), 50 μg/ml (n=7) and 100 μg/ml (n=3). After 2 h, cells were exposed to normoxic (A) or hypoxic (B) conditions for 48 h. C) Normoxic and hypoxic CX− tumor cells were irradiated with a dose of 4 Gy Number of clones was related to completely untreated CX− tumor cells. Columns indicate radiation-sensitivity of normoxic (left panel) and hypoxic (right panel) CX− tumor cells after incubation with either Hsp70 protein or BSA (50 μg/ml). Data are means ± se of least 3 independent experiments. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001.