Due to the dark non-specific background staining with the initial IHC protocol used to screen the array, we then used an optimized protocol to test for EpCAM expression in formalin-fixed, paraffin-embedded sections of normal feline oral tissue, two feline mammary carcinomas, one with unaffected normal mammary and cutaneous epithelium, and an oral squamous cell carcinoma. This evidence concerns the gene EPCAM and breast carcinoma.