An editorial in the July issue of the Journal of Clinical Investigation (2006;116: 1740-1) by the journal's executive editor, Ushma S. Neill, entitled "Stop Misbehaving!"
notes that the editors often find evidence of "blot doctoring" - instances in which software such as Adobe Photoshop has been used to augment contrast, sharpen images, edit out noise. The editor coments "Though several of the articles had successfully passed through the peer review process, we did not publish those papers, as the intent clearly was to deceive — and there was no way to tell whether other data had been similarly contrived.
The editorial further notes that it is not appropriate to edit multiple images of cells into one image or reuse previously published images (including those that have been cropped or otherwise edited to make them appear new or different).
The editor also points out a few other issues that seem to keep cropping across the spectrum of scientific publishing -- don't submit the same article to more than one journal at once, be transparent as possible about conflicts of interest, openly discuss authorship and attribution of a paper.
Neill concludes the editorial, "As I stated before, by and large, most of our authors are honest scientists who are indeed beyond reproach, but the pressure to "publish or perish" is felt by all researchers. It is your responsibility to consistently act ethically when performing and presenting your research. You need to be vigilant about what is being done in your laboratories, and you must foster honest and open lines of communication with your students, colleagues, and peers. Failure to do so only hinders our ability to gain true insight into physiologic and pathophysiologic processes, which is what we’re all striving to achieve