HTRA2 and colorectal carcinoma: The real-time PCR method was used to quantify the relative mRNA levels of HTRA1, HTRA2 and both variants of HTRA3: HTRA3L and HTRA3S. A significant difference in the HTRA1 mRNA levels between CRC tissue and unchanged colorectal mucosa has been found; the mRNA level of HTRA1 was 1.8-fold higher in tumor tissue when compared to control tissue (Figure 1A).