HOXC4 and cholangiocarcinoma: HOXC4 was highly upregulated in CCA compared to CCA NATs (p < 0.0001), showing a 25.70-fold increase compared to HCC NATs (p < 0.0001), a 19.96-fold increase compared to HCC (p < 0.0001), a 4.31-fold increase compared to CRLM (p < 0.001) and a 2.73-fold increase compared to PCLM (p < 0.05).