IGFBP4 and rickets: Another prospective study of children with rickets as a reference population was conducted in 2010 by Bereket et al. Although their main intent was to identify the in vivo role of the insulin-like growth factor binding protein 4 (IGFBP-4) in this group, the most interesting results came from the effect of vitamin D supplementation therapy on the other growth markers: IGF-1 and IGFBP-3.