Complex sentence: After the breast cancer cells have traveled away from the primary tumor, they establish a tight interaction with the bone microenvironment and secrete osteolytic factors capable of osteoclast formation and bone resorption.
Split into simpler sentences: After the breast cancer cells have traversed away from the primary tumor, they establish a tight interaction with the bone microenvironment. They secrete osteolytic factors capable of osteoclast formation and bone resorption.