2006; Wen et al. 2008). p38 activation mediates tamoxifen resistance in estrogen receptor‐positive breast tumors (Gutierrez et al. 2005). p38 inhibition enhances the sensitivity of multiple myeloma cells to arsenic trioxide and bortezomib (Wen et al. 2010). The gene discussed is ESR1; the disease is breast neoplasm.