We succeeded in detecting Rac/Cdc42 activation in human colon cancer FFPE tissues with various patterns, strikingly in the invasive front, of which activity was correlated with clinicopathological factors such as lymphatic vessel invasion, raising the value for predicting invasion and metastasis in various types of cancers; although it needs to be noted that the binding to and detection of other Rac members, such as Rac2 and Rac3 and/or Cdc42, cannot be excluded in patient-derived material. Here, CDC42 is linked to colonic neoplasm.