We have already used this protocol successfully for quantitative proteomics of FFPE cores and sections in breast cancer patient-derived xenografts for precise quantitation of PTEN [59], AKT1/2, and PIK3CA (publication in preparation), as well as in clinical samples of non-small cell lung cancer (NSCLC) for quantitative assessment of proteins in the PDL1-axis (publication in preparation). This evidence concerns the gene PIK3CA and breast cancer.