We investigated cytosolic and mHsp70 levels in isogenic human colon carcinoma sublines CX+/CX−, mouse mammary carcinoma cell lines 4 T1 ctrl/4 T1 Hsp70 knock-down (4 T1 Hsp70 KD), human lung carcinoma cell sublines H1339 ctrl/H1339 HSF-1 KD and EPLC-272H ctrl/EPLC-272H HSF-1 KD. The gene discussed is HSPA1A; the disease is breast carcinoma.