Promotes the rapid degradation of CTNNB1 and participates in Wnt signaling as a negative regulator. APC activity is correlated with its phosphorylation state. Activates the GEF activity of SPATA13 and ARHGEF4. Plays a role in Hepatocyte growth factor (HGF)-induced cell migration. It is required for MMP9 up-regulation via the JNK signaling pathway in colorectal tumor cells. Acts as a mediator of ERBB2-dependent stabilization of microtubules at the cell cortex. It is needed for the localization of MACF1 to the cell membrane which is critical for its function in microtubule stabilization. Here, MAPK8 is linked to colorectal neoplasm.