ESR1 and breast cancer: In fact, treatment of ER+ BC cells with ADPN levels similar to those observed in obese patients triggers a multiprotein complex (AdipoR1/APPL1/IGF-IR/c-SRC) responsible for activating MAPK, which subsequently transactivates the ER to translocate to the nucleus and upregulate estrogen-dependent genes to promote cell growth [58,59,60] (Figure 2).