Which viral component is responsible for inducing a host cell to take in an influenzavirus by endocytosis?

The viral component that is responsible for inducing a host cell to take in an influenza virus by endocytosis would be hemagglutinin. It is a glycoprotein that can be found in the surfaces of an influenza virus and is essential to its entry to hosts. It is the substance that is responsible for allowing the virus to bind to cells especially cells in the respiratory tract. It also causes the RBC or the red blood cells to agglutinate or clump together. The hemagglutinin is cylindrical in shape and is 13.5 nm in length. It has 18 different antigens wherein they are named H1 to H18. 

The  answer is 1 amu.