Similar to the blockade of osteosarcoma progression in femoral bone by the mAb 5f4, the de novo invasion of prostate epithelial cells induced by exposure to a stiff microenvironment can be blocked by the mAb A5/158, which recognizes an epitope in the second CTLD (CTLD2) of Endo180 9. This evidence concerns the gene MRC2 and osteosarcoma.