NRG1 and cholangiocarcinoma: Moreover, among the oncogenic fusions identified in mPDAC samples, we observed fusions involving FGFR2 (two patients; fusion partners BICC1 and SORBS1) and NRG1-ATP1B1 (one patient) in three of 14 (21%) cholangiocarcinoma samples, all of which were contained in Cluster 2.