In 1985, the HER2 oncogene was discovered by Axel Ullrich, a young scientist at Genentech. The new oncogene revealed in rat cells was called ﾓneu.ﾔ

p>The human version of this gene, called HER2 (and ErbB2), is overexpressed in about 20% to 25% of breast cancers (known as HER2-positive breast cancers) and is associated with more aggressive disease and a poor prognosis.