IGF1R and cancer: Since increased levels of IGF1 ligand can mediate the formation of more IGF1R/IR HRs, preventing IGF bioactivity by blocking the interaction of IGFs with IGF1R/IR heterodimeric receptors, which play major roles in mediating the IGF/IGF1R signaling axis, might contribute to the anti-tumor activity of figitumumab in cancer cells dependent on IGF1R signaling.