MAPK8 and breast neoplasm: In this study, we provided new evidence that miR-21 expression is controlled by an upstream promoter/enhancer containing AP-1 binding sites in MDA-MB-468 cells while chromatin immunoprecipitation (ChIP) assays demonstrate that stimulation of miR-21 production by HA is JNK and c-Jun-dependent in breast tumor cells (Figure 4).