Background Nicotine is the major addictive component of tobacco smoke. Although nicotine
is generally thought to have limited ability to initiate cancer, it can induce cell proliferation
and angiogenesis in a variety of systems. These properties might enable nicotine to facilitate
the growth of tumors already initiated. Here we show that nicotine significantly promotes the
progression and metastasis of tumors in mouse models of lung cancer. This effect was
observed when nicotine was administered through intraperitoneal injections, or through over …

After publication of this article [1], concerns were raised about the second and third Z0-1
NNK+ Nicotine panel in Fig 5E. Specifically, the left side of the middle NNK+ Nicotine panel
appears to overlap with a region on the right side of the rightmost NNK+ Nicotine panel. The
authors commented that this was due to an error made during the preparation of the figures
and that whilst these panels represent the same experimental conditions, they are intended
to be representative images of tissue taken from different mice. The authors provided for …