IDO1 and colorectal carcinoma: Our finding of high expression of IDO1 at the proteogenomic levels coincides with TCGA (The Cancer Genome Atlas) and other studies, where higher expression of IDO1 at the mRNA level was observed in primary CRC (Guil-Luna et al., 2020; Kitsou et al., 2020; Le Naour et al., 2020).