JUN and neoplasm: Nevertheless, our data suggest that Jun is at least partially involved in the transcriptional activation of Ets21C and Mmp1. In addition to the JNK pathway-dependent upregulation of Ets21C in a tumor background, we found that Ets21C and Mmp1 are induced if we activate the JNK pathway in wild-type eye discs (Fig. 2g,h).