Localization of Fluorescein-labeled Anti- bodies of Epidermal Proteins In Normal and

SUMMARY-Antisera were prepared in rabbits against mouse and human epidermal proteins and mouse squamous cell carcinoma proteins. The dis-tribution of these proteins in mouse epidermis undergoing malignant trans-formation and in human cancers was determined with the fluorescein-labeled antibody technique. The urea- and alkali-extractable proteins of epidermis 4 days after the hair was plucked and squamous cell carcinomas of mice, human epidermis, and its extractable proteins all shared common antigenic determinants, but specificity of staining revealed differences. The epider-mises of mice had antigens not detected in the carcinomas; these carcinomas were antigen-deficient in epidermal proteins. Squamous cell carcinomas of the tongue, larynx, floor of the mouth, and bronchus (lung) of man were stained intensely with the antisera prepared against (a) normal human epidermis, (b) the alkali-extractable proteins and tonoAbrin of human epi-dermis, and (c) urea-extractable proteins of mouse squamous cell carcinomas. Malignant melanomas did not stain with any of these antisera. The anti