For example, ALX4 was found to bind the P3 site in human cranial neural crest cells (Cain et al., 2025; Kim et al., 2024); Phox2a enriched for P3 dimer sites in cortical motor neurons (Cain et al., 2023; Mazzoni et al., 2013); and PHOX2B predominantly binds to only P3 sites in KELLY, BE2C, and CLBGA neuroblastoma cell lines (Boeva et al., 2017; Cain et al., 2023; Durbin et al., 2018). This evidence concerns the gene ALX4 and neuroblastoma.