ATF4 and cholangiocarcinoma: Moreover, several RNAs were also differentially present in EVs derived from CCA versus PSC, in particular, the mRNA transcripts paraoxonase 1 (PON1), activating transcription factor 4 (ATF4), and phosphoglycerate dehydrogenase (PHGDH), the lncRNAs metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and LOC100190986, and the small nucleolar RNA (snoRNA) SNORA11B.