Acts as a negative regulator of cell migration, invasion, and metastasis downstream of p53/TP53, through inhibition of Arp2/3 complex-mediated actin polymerization (PubMed:32128961). Via its association with the multisubunit axonemal dynein complex, is potentially involved in the regulation of cilia function (By similarity). May play a role in osteogenesis of dental tissue-derived mesenchymal stem cells (By similarity). Interacts with ACTR2; this interaction reduces binding of the Arp2/3 complex to the VCA domain of nucleation promoting factors (PubMed:32128961). Part of the multisubunit axonemal dynein complex formed at least of two heavy chains and a number of intermediate and light chains. Found in a associated with the catalytic heavy chain DNAH2, the intermediate chain DNAI4, and the light chain DYNLT1 (By similarity). Up-regulated at the transcriptional level by TP53. A rare heterozygous in-frame DNAI3 deletion encompassing exons 14-17 has been found in a fetus with encephalocele. Overexpression of human DNAI3 RNA lacking exons 14-17 in zebrafish embryos also results in similar brain malformations, suggesting that DNAI3 defects might be involved in encephalocele formation.