GJA3 (Connexin 46) is a component of lens fiber gap junctions. Congenital cataract is the leading cause of visual disability in children. Defects in GJA3 are a cause of zonular pulverulent cataract type 3. Both normal hypoxic tissue (lens) and adaptive hypoxic tissue (breast tumor) utilize GJA3 as a protective strategy from hypoxia. GJA3 may provide a new direction for drug development for breast cancer treatment.