NFKB1 and breast cancer: The other type of mechanisms is compensatory activation of downstream or parallel signaling pathways (off-target), such as RAS-RAF-MEK-ERK, PI3K-PTEN-AKT-mTOR, IGF1R pathway, NF-κB pathway et al., which were common in both lung and breast cancer with acquired resistance to respective targeted therapy (1–4) and could be overcome by combination therapies.