EGFR and colorectal carcinoma: As to the detection of protein levels, we found that phosphorylated EGFR expression was significantly downregulated in both cell lines after 24 h of incubation with tetrac or its combination with heteronemin (Figure 3A), while total EGFR protein was significantly downregulated after combined treatment in HCT-116 cells (KRAS MT CRC; Figure 3B).