STK4 and colorectal carcinoma: For such a purpose, eight CRC TAAs were selected for the study: GTF2B, MAPKAPK3, PIM1, PKN1, SRC, STK4, SULF1, and p53, where PIM1, PKN1, SRC, and SULF1 (and p53) are difficult-to-express and/or purify proteins and GTF2B, MAPKAPK3, and STK4 are easy-to-express proteins used as controls to ascertain whether this approach maintains their previously described CRC diagnostic ability 7, 9.