ITGA5 and neoplasm: These findings include that (1) CAFs contribute to the tumor growth of breast tumors, as seen in our preclinical study; (2) CAFs, as well as CTCs, shed in blood circulation; (3) ITGA5 can be considered a new marker for cCAFs; (4) treatment with chemotherapy (L-Dox) induced increased incidence and numbers of cCAFs and CTCs; and (5) cCAFs and CTCs were found to form clusters in chemotherapy-treated mice.