PDK1 and neoplasm: Moreover, the downregulation of phosphorylation of the primary PDK1 target Akt, which has been reported in several celecoxib-treated tumour cell lines (Hsu et al, 2000; Arico et al, 2002; Song et al, 2002; Kulp et al, 2004), is not consistently observed in all tumour cells (Kern et al, 2002; Kardosh et al, 2005), even though apoptosis is similarly induced by drug treatment.