Studies on the expression of PLK1 have been performed on carcinomas of lung (Wolf et al, 1997), head and neck (Knecht et al, 1999), oesophagus and stomach (Tokumitsu et al, 1999), skin (Kneisel et al, 2002), breast (Wolf et al, 2000), brain (Dietzmann et al, 2001), endometrium and ovary (Takai et al, 2001a, 2001b). This evidence concerns the gene PLK1 and lung carcinoma.