In order to reveal micro-foci of tumor localization at the molecular level, the expression of two TAA genes, MAGE-A1 and MAGE-A2, which may be expressed by both bladder and renal cancers [17, 18], was comparatively analyzed in tumoral and autologous apparently free-of-tumor bladder and kidney tissues. The gene discussed is MAGEA2; the disease is renal carcinoma.