CHEK2 and cancer: Phosphosites that showed statistically significant alterations and were not identified or quantifiable in the PhosphoRS-derived data included both known functional sites on established cancer genes such as CHEK2_S379 (known to induce CHEK2 enzymatic activity (42)) and EGFR_S1071 (associated with EGFR desensitization (43)), as well as sites on less explored genes such as RIPK2_S176 (known to induce RIPK2 enzymatic activity (44)) (Fig. 6B).