HW: How can normal HER2 promote cell proliferation even though it does not directly bind to any extracellular growth factors?,”Answer: None of the abovepromote tumor proliferation for 2 reasons: 1) Her2 can form heterodimers with any other Her family members (1, 3, 4). This is going to sensitize the cell to basically grow at very low extracellular concentrations of EGF that normally wouldn’t be enough to activate Her1 or Her4 homodimers. Her2 coming in and forming and activating a large number of other receptors that would normally be monomeric. The other thing that happens, new insight, when you overexpress Her2

HW: How can normal HER2 promote cell proliferation even though it does not directly bind to any extracellular growth factors?,”Answer: None of the abovepromote tumor proliferation for 2 reasons: 1) Her2 can form heterodimers with any other Her family members (1, 3, 4). This is going to sensitize the cell to basically grow at very low extracellular concentrations of EGF that normally wouldn’t be enough to activate Her1 or Her4 homodimers. Her2 coming in and forming and activating a large number of other receptors that would normally be monomeric. The other thing that happens, new insight, when you overexpress Her2

it can homodimerize all by itself (and Her2 doesn’t bind to EGF) so now you can have tumor cells that are proliferating in the complete absence of EGF.”