This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
The major function of Major Intrinsic Protein 26 (MIP–26) is – 
Select and explain. 
A. Glucose transport in lens, B. Transport of water in lens, C. Diffusion barrier, D. Capsule of lens
B: Transport of water in lens
Answer: B: Transport of water in lens 
Explanation: Major intrinsic protein of the lens belongs to the super .family of aquaporins and is classified as aquaporin 0. MIP 26 or aquaporin 0 is permeable to water (water channels) and glycerol (glycerol channels). It serves two major functions to maintain the transparency of the lens
Transport of water across the lens
Transport of glycerol across the lens
Aquaporin 0 or MIP mutations have been postulated to result in the formation of cataracts (loss of transparency of lens).