DM1 is derived from the maytansinoid toxin,which induces cell death by blocking the process of tubulin polymerization.Although DM1 has a narrow therapeutic window for treating cancer,this is expanded by its connection to trastuzumab, which specificallydirects the cytotoxin to cancerous cells that have an excessive amountof the HER2 receptor tyrosine kinase. The gene discussed is ERBB2; the disease is cancer.