Similarly, when we silenced the expression of MEKK1 in human breast cancer cell MDA-MB-453 (MDA-MB-453-shMEKK1-1), in which both JNK2 and p-JNKs were presented, down-regulation of p-JNKs, increased expression of FRA1 and enhanced cell migration were found (Supplementary Figure 3B, 3C, 3F). Here, MAPK9 is linked to breast cancer.