Cytokeratins are intermediate filament keratins found in the intracytoplasmic cytoskeletonof epithelial tissue There are two types of Cytokeratins: the low weight, acidic type Icytokeratins and the high weight, basic or neutral type II. Cytokeratins are usually found inpairs comprising a type I Cytokeratin and a type II cytokeratin. The high molecular weightcytokeratins, which are the basic or neutral cytokeratins, comprise subtypes CK1 (67), CK2(65. 5), CK3 (64), CK4 (59), CK5 (58), CK6 (56), CK7 (54), CK8 (52. 5) and CK9. The lowmolecular weight cytokeratins, which are the acidic cytokeratins, comprise subtypes CK10(56. 5), CK12 (56), CK13 (53), CK14 (50), CK16( 48), CK17 (46), CK18 (45), CK19(48) andCK20(46).