In the article on expression diagnostic for cancer of unknown primary in the May 15, 2005 issue of Cancer Research (1), a minus sign was omitted from the equation for calculating the fold change ratio between target genes and the average expression of a panel of control genes for analysis of quantitative RT-PCR data on page 4032. The equation should have read as follows: X = 2-ΔCt; where ΔCt = Ct target - Ct average endogenous controls.

1
Tothill RW, Kowalczyk A, Rischin D, Bousioutas A, Haviv I, van Laar RK, Waring PM, Zalcberg J, Ward R, Biankin AV, Sutherland RL, Henshall SM, Fong K, Pollack JR, Bowtell DDL, Holloway AJ. An expression-based site of origin diagnostic method designed for clinical application to cancer of unknown origin.
Cancer Res
 
2005
;
65
:
4031
–40.
View Original Article
©2005 American Association for Cancer Research.
2005