HSPA1A and neoplasm: Since tumor sublines with low or missing mHsp70 expression in both isogenic cell systems (CX−, 4 T1 Hsp70 KD) showed higher γH2AX fluorescence intensities than their high mHsp70 expressing counterparts, irrespectively of their cytosolic Hsp70 levels we speculate that mHsp70 might be involved in the protection of tumor cells against radiation-induced stress.