ALCAM and neoplasm: CD166 (ALCAM) is a cell surface molecule that is a member of the immunoglobulin superfamily. CD166 is widely expressed in various tumors, and its biological functions in tumor stem cells primarily encompass the facilitation of tumor growth and metastasis, enhancement of tumor cell survival, modulation of immune response, involvement in the formation of the tumor microenvironment, as well as regulation of self-renewal and differentiation processes within tumor stem cells