The product contains the polyhedrin protein co-crystalized with Human Noggin. Noggin belongs to a group of diffusible proteins that bind to ligands of the TGF-β family, and regulate their activity by inhibiting their access to signaling receptors. During embryogenesis, Noggin is a secreted homodimeric glycoprotein that is an antagonist of bone morphogenetic proteins (BMPs) at specific times, for example, during neural tube, somite and cardiomyocyte growth and patterning. During culture of human embryonic stem cells (hESC) or neural stem cells under certain conditions, addition of Noggin to antagonize BMP activity may allow stem cells to proliferate while maintaining their undifferentiated state, or alternatively, to differentiate into dopaminergic neurons.