The beta 2 subunit of mouse hemoglobin (HBB2) has been identified as soluble factor from mouse lungs that exhibits cytostatic/cytotoxic activity against neuroblastoma lung micrometastases. The beta subunit of human hemoglobin (HBB) has been found to have similar activity. Methods of using these proteins and fragments thereof in the treatment of cancer and inhibition of metastasis are provided, along with methods of screening a subject for micrometastases by detecting HBB in a biological sample.
