DOG 1 (an acronym for “Discovered On Gist”) is primarily used by pathologists in the diagnosis of gastrointestinal stromal tumor (GIST), often in conjunction with CD 117 stain. Sensitivity in this setting ranges from 87-97%. Staining is membranous and cytoplasmic. It is also useful in the identification of PDGFRa mutant GIST, which is more likely to be CD117 and CD34 negative. Positive staining can be seen in a variety of other tumors including acinic cell carcinoma, chondroblastoma, cylindroma, chromophobe renal cell carcinoma and renal oncocytoma.