Plays a role in ciliogenesis. . [Isoform 1]: Pericentriolar protein required to maintain mitotic spindle pole integrity (PubMed:21224392). Required for the centrosomal accumulation of PCM1 and the recruitment of centriolar satellite proteins such as BBS4. Via association with PCM1 may be involved in primary cilia formation (PubMed:23110211). Required for CEP63 centrosomal localization and its interaction with WDR62. Together with CEP63 promotes centriole duplication. Promotes the centrosomal localization of CDK2 (PubMed:26297806). {ECO:0000269|PubMed:21224392, ECO:0000269|PubMed:23110211, ECO:0000269|PubMed:26297806}. [Isoform 4]: The secreted form is a mediator of progesterone that by acting on the phospholipase A2 enzyme interferes with arachidonic acid metabolism, induces a Th2 biased immune response, and by controlling decidual natural killer cells (NK) activity exerts an anti-abortive effect (PubMed:12516630, PubMed:14634107, PubMed:3863495). Increases the production of Th2-type cytokines by signaling via the JAK/STAT pathway. Activates STAT6 and inhibits STAT4 phosphorylation. Signaling via a not identified receptor seems to implicate IL4R and a GPI-anchored protein (PubMed:16393965, PubMed:25218441). {ECO:0000269|PubMed:12516630, ECO:0000269|PubMed:14634107, ECO:0000269|PubMed:16393965, ECO:0000269|PubMed:25218441, ECO:0000269|PubMed:3863495, ECO:0000305|PubMed:11407300}. This is the function of PIBF1 (progesterone immunomodulatory binding factor 1, Ensembl gene identifier ENSG00000083535).