p53, Hsp70 and EGFr immunohistochemical expression in UGBM1, U-87MG and MO59J spheroids following irradiation. Immunostaining score was calculated for non-treated (control) or irradiated (5 Gy) as determined 24 h (left column) and 6 days (right column) after treatment. Arbitrary scoring system was calculated as described in Methods section. Data was plotted as the mean ± SD of three different experiments. *Significantly different from control (p < 0.05).