SPHK1 and cholangiocarcinoma: ERBB2-induced gene expression profiles as determined by microarray analysis included cytokeratin 20 (Krt20), Sry-related HMG box gene-17 (Sox17), amphiregulin (Areg), MUC1, and sphingosine kinase 1 (Sphk1) among the genes strongly correlated with tumor growth and metastases of CC cells [42].