Other K+ channels, such as inward rectifier channel Kir3.1 (KCNJ3) and two pore domain channel K2P9.1 (KCNK9), are associated with lymph node metastasis and proto-oncogenic activity, respectively, with K2P9.1 showing gene amplification in 10% of BC cases (Stringer et al., 2001; Mu et al., 2003). The gene discussed is KCNK9; the disease is breast cancer.