Inhibitor of the serine/threonine-protein kinase pak4/pak5 (By similarity). Acts by binding pak4/pak5 in a substrate-like manner, inhibiting the protein kinase activity (By similarity). Required for the proper migration of neural crest cells during embryonic development, probably by inhibiting pak4/pak5 (PubMed:17314132). Interacts with pak4/pak5. Primarily detected in migrating neural crest cells and their derivatives during embryogenesis. Expression is regulated by the transcription factor AP-2-alpha/tfap2a. Contains 2 Inka boxes (also named iBox or inca box). The Inka boxes bind and inhibit PAK4 by binding a substrate-like manner. Dramatic reduction in craniofacial cartilage formation. Belongs to the INKA family.