PAGE4 gene family tree. Duplication events are marked with blue squares. Gene names, Ensembl gene ID, and the species are given at the tips of the tree. Circles represent expression patterns, with circle color corresponding to the tissue of highest expression of the respective gene and circle size approximating the expression level. It is likely that homologs of PAGE4 are placenta-specific expressed in other eutherian species, as suggested by the study in the elephant (Hou et al. 2012); however, we could not assess this pattern, as placenta samples from other primates were not available to our study. The absence of expression of PAGE3 and PAGE5 in orangutan is likely explained by the unavailability of testis samples from this species to our study.
