Useful markers of epithelial differentiation are
The protein making the bulk of keratohyalin granules is fillagrin. Also sulfur-rich protein loricin is present.  Fillagrin and loricin are useful markers of epithelial differentiation. Involucrin contributes to the 'Cornified cell envelope' in the cell membrane of keratohyalin cells.
Fillagrin
Loricin
Both
None