Tumor epithelial cells expressed well-characterized markers of CRC or GC [18, 40] (KRT7, KRT17, ELF3, CEACAM6, FABP1, FABP5, SPINK1, REG4, TFF3) (Additional file 2: Fig. S1A, S1B). Here, CEACAM6 is linked to colorectal carcinoma.