Prolactin also stimulates proliferation of oligodendrocyte precursor cells. PDGF is also known to maintain proliferation of oligodendrocyte progenitor cells. Olig2 is one of the most important transcription factors involved in oligodendrocyte production. This indicated that neuregulin is not necessary for the proliferation of oligodendrocyte multipotent precursor cells. One early study focused on the signaling of oligodendrocyte myelination by regenerating peripheral axons. Oligodendrocyte abnormalities appear to be crucially involved. For instance, SEMA3s modulate the recruitment of oligodendrocyte precursor cells and their differentiation into oligodendrocytes. Astrocyte and oligodendrocyte glial cells were pooled for these results. An oligodendrocyte can myelinate up to 50 axons. Laminin, a component of the extracellular matrix, plays an important role regulating oligodendrocyte production. The experiments showed improved oligodendrocyte survival, and remyelination increased. However, it is not clear whether all oligodendrocyte progenitors undergo this sequence of events. For example, COX-2 has been implicated in oligodendrocyte death in animal models of demyelination. Each oligodendrocyte forms one segment of myelin for several adjacent axons. Klotho is required for oligodendrocyte maturation, myelin integrity, and can protect neurons from toxic effects.