Consequently, TRAF2 will be polyubiquitinated and activated, likely through a self-ubiquitination mechanism, resulting in the activation of ERK1/2 and particularly JNK signaling and subsequent AP-1-dependent expression and activation of MMPs (e.g., MMP1) and finally, promotion of invasion and metastasis of cancer cells (Fig. 6). Here, MMP1 is linked to cancer.