ROBO1 and cholangiocarcinoma: After GO enrichment of upregulated genes in CCA from the GEPIA database, the STRING results showed that SFN, cyclin dependent kinase inhibitor 2A (CDKN2A), E2F transcription factor 1 (E2F1), and roundabout guidance receptor 1 (ROBO1) were related to cell apoptosis and proliferation (Figure 1b).