1. Place five-micron thick tissue sections on glass slides coated with poly L-lysine or APTES.
2. Deparaffinize and rehydrate sections as usual.
3. Block endogenous peroxidase as usual.
4. Wash sections in wash-buffer for 2 x 5 minutes.
5. Cover sections with the pepsin solution (usually 0.2mL per section) and place the slides at 37°C for 10 minutes in a humidified chamber.
6. Wash sections in wash buffer for 2 x 5 minutes.
7. Block nonspecific sites with normal serum as usual.
8. Place optimally diluted primary antibody on the sections (incubation time and temperature for a given set of experimental conditions should be determined by the investigator).
9. Wash sections in buffer for 2 x 5 minutes.
10. Remaining procedure is same as routinely performed in your laboratory.