In the year since their 2008 preliminary ranking, Cell Stem Cell and Cell Host and Microbe saw their Impact Factors surge, according to new data released in the 2009 Journal Citation Reports(c) published by ThomsonReuters.   The Impact Factor is a measure of the frequency with which the average article in a journal has been cited in a particular year. The Impact Factor helps to evaluate a journal's relative importance, especially when compared with others in the same field.

In the report released June 17, Cell Stem Cell's rating rose to 23.563 - a growth of 40% from the journal's previous score. Cell Host and Microbe ranks 13.021 - boasting an increase of 75% from the journal's 2008 Impact Factor.

 Cell,  an imprint of Elsevier, remains the number one research journal in the Cell Biology and Biochemistry Molecular Biology subject categories, with an Impact Factor of 31.152. 

 The ranking also reveals that Cancer Cell continues to grow with a 2009 rating of 25.288. Molecular Cell saw an impressive 13% increase to 14.608, and The American Journal of Human Genetics, a Society journal within the Cell Press publishing portfolio, saw its Impact Factor jump 21% in 2009 to 12.303. 

The 2009 Journal Citation Reports(c) ranks the Cell Press journals' Impact Factors as follows:

 Cancer Cell (25.288) Cell (31.152)
Immunity (20.589)
Current Biology (10.992)
Structure (5.904)
Molecular Cell (14.608)
Cell Metabolism (17.35)
Cell Stem Cell (23.563)
Cell Host and Microbe (13.021)
Chemistry and Biology (6.523)
Neuron (13.26)
Developmental Cell (13.363)
Trends in Biochemical Sciences (11.572)
Trends in Cognitive Sciences (11.664)
Trends in Genetics (8.689)
Trends in Microbiology (6.894)
Trends in Molecular Medicine (11.049)
Trends in Neuroscience (12.974)
Trends in Plant Science (9.883)
Trends in Biotechnology (6.909)
Trends in Cell Biology (12.115)
Trends in Ecology and Evolution (11.564)
Trends in Endocrinology and Metabolism (6.562)
Trends in Immunology (8.768)
Trends in Parasitology (4.298)
Trends in Pharmacological Sciences (9.064)
Society Journals, American Journal of Human Genetics (12.303)
Biophysical Journal (4.39)