They activate ErbB2 receptors in the Schwann cell microvilli, which results in the activation of the mitogen-activated protein kinase (MAPK).[13] Although MAPK activity is observed, the injury sensing mechanism of Schwann cells is yet to be fully understood. The sensing is followed by decreased synthesis of myelin lipids and eventually stops within 48 hrs. The myelin sheaths separate from the axons at the Schmidt-Lanterman incisures first and then rapidly deteriorate and shorten to form bead-like structures.