RIPK4 and Bartsocas-Papas syndrome 1: While the kinase function of IKKα is dispensable for keratinocyte differentiation (Hu et al., 2001), RIPK4 phosphorylates IRF6 to drive nuclear translocation and regulate its transactivator activity; mutations in the kinase domain of RIPK4 that underlie Bartsocas Papas syndrome disrupt this activity (De Groote et al., 2015; Kwa et al., 2014).