Cellular retinoic acid-binding protein in virus-induced Shope papillomas of rabbit skin.

Cellular retinoic acid-binding protein (cRABP) was detected in the cytosol of virus-induced papilloma (Shope) of rabbit skin. The Shope papilloma cRABP showed the same ligand specificity and sedimentation value (2S) as was found in other animal species. The level of cRABP in the papillomatous tissue was significantly higher than that in the normal rabbit skin and increased in accordance with the growth and development of the tumor, reaching a peak about 40 days after the inoculation of the Shope papilloma virus. Although this binding capacity was about 15 times greater than in the normal skin, the level of cRABP in the transplantable carcinomas Vx2 and Vx7, both originating from the virus-induced papillomas over 20 years ago, was much the same as in normal rabbit skin.