SLC18A3 and intrahepatic cholangiocarcinoma: Among the five markers, significant upregulation of TH (p = 0.005), a biomarker of SNS [24], was observed in patients with PNI from the ZS-ICC cohort compared to those in patients without PNI, whereas no difference in pan-neural markers such as ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1/PGP9.5) [25] (p = 0.292), beta-tubulin III (TUBB3) [26] (p = 0.656), synapsin (SYN) [27] (p = 0.612), and PNS biomarker vesicular acetylcholine transporter (VACHT) [28] (p = 0.266) was detected (Fig. 2b, c).