PRKG1 and neoplasm: Fig. 1 shows representative staining patterns for PGK 1. Lack of staining or weak staining of PGK 1 (i.e., ≤20% of tumor cells expressed PGK) was classified as PGK1-negative expression and moderate to strong staining (i.e., >20% of tumor cells expressed PGK1) was classified as PGK1-positive expression. A total of 7 (32%) of the 22 tumors were PGK1 positive and 15 (68%) samples were PGK1 negative (Table 1).