SRC and cancer: Since high Src levels were found to completely eliminate Cad11, and Cad11 is required for metastasis [37, 43, 44], it appears that actual metastatic tumors cannot possibly possess such high levels of Src activity; that is, a fine balance between Src and Cad11 levels may be required for the formation of a metastatic tumor, as observed in medium-Src-expressing cells, i.e. this level of Src activity may be more relevant to cancer in vivo.