 It is also known to bind the caveolin 1, a protein which regulates p21ras, PKC and growth response factors.There are currently five known isoforms of neurofibromin (II, 3, 4, 9a, and 10a-2) and these isoforms are generated through the inclusion of alternative splicing exons (9a, 10a-2, 23a, and 48a) that do not alter the reading frame.These five isoforms are expressed in distinct tissues and are each detected by specific antibodies.