NTRK2 and cancer: Using the methylation profile we previously generated through 450K microarray, we found NTRKs gene, including NTRK1, NTRK2 and NTRK3, had more frequently methylated promoters in CRC samples when compared with matched normal mucosae (NTRK1, cancer = 0.444, normal = 0.397, P = 0.012; NTRK2, cancer = 0.251, normal = 0.167, P < 0.001; NTRK3, cancer = 0.395, normal = 0.144, P < 0.001; Fig. 2; Additional file 1: Table S2).