MAPK3 and neoplasm: Furthermore, activated ERK1/2 and/or increased levels of ERK1/2 have been reported in a variety of human tumour cell lines (Hoshino et al, 1999) and epithelial cancer tissues such as breast (Sivaraman et al, 1997; Adeyinka et al, 2002), kidney (Oka et al, 1995), colon (Sebolt-Leopold et al, 1999) and head and neck cancers (Albanell et al, 2001).