The majority of changes in mRNA (19 or 20 out of 20 analyzed CRC samples) levels were associated with comparable changes in protein levels, with the exception of PCSK9, which showed a large mRNA increase but a small and not significant drop at the protein level, and for GPI, which remained essentially unchanged in the majority of CRC (17 out 20) (Additional file 5: Figure S3). Here, PCSK9 is linked to colorectal carcinoma.