RAD51 and neoplasm: RAD51 exhibited instead a more diffuse staining pattern in both the cytoplasm and nucleus as expected in a pre-treatment tumor biopsy (i.e. before exposure to radiation, no-stress condition), although cases with high expression levels more often displayed RAD51 foci; this latter feature is in line with previous reports showing that when RAD51 is overexpressed, foci and higher order structures are seen even in the absence of induced DNA damage and even when cells are not in S phase [28].