HSPB1 and neoplasm: In addition, the high surface expression of mouse HspB1 on 4T1 tumors significantly increases their ability to grow within the abdominal breast gland and to successfully metastasize and colonize the lungs and the interaction between host effector cells and tumors expressing high levels of surface-bound HspB1 results in abrogation and/or deactivation of host anti-tumor responses [25,37,41-43].