NFKB1 and neoplasm: However, several factors including tumor heterogeneity [144], epigenetic regulation by miRNAs [31], synergistic effects of multiple signaling pathways such as Akt/PI3K, MAPK/ERK, NF-κB/IL-6, mTOR, Hedgehog, and somatostatin receptor have been shown to contribute to drug resistance in these tumor cells.