HER2 is a protein that acts on epidermal tissue growth. It therefore has a stimulating effect on cell
multiplication. HER2 contains 1,255 amino acids. This protein can be found in cancerous tumor
cells in 1/3 of cases of breast cancer
. If it mutates, either by an increase or decrease in the number of its genes, this can cause the spread of cancerous cells. When tumors
are linked to HER2, this is a life-threatening condition, as the cancer
is more aggressive and metastatic.