In a recent adenovirus Cre-induced KrasG12D, p53fl/fl, Smad4fl/fl model of lung cancer, increased metastasis was associated with Smad4 LOF and Pak3 activation, the latter identified as a downstream effector of Smad4 via the PAK3-JNK-Jun pathway72. Here, MAPK8 is linked to lung carcinoma.