These factors are ubiquitously expressed and it is proposed that defects in a ubiquitous factor ( a protein expressed everywhere ) should only cause disease in the retina .
The retinal photoreceptor cells have a far greater requirement for protein processing .
These factors are ubiquitously expressed and it is proposed that defects in a ubiquitous factor ( a protein expressed everywhere ) should only cause disease in the retina because the retinal photoreceptor cells have a far greater requirement for protein processing .