With our sincere gratitude and appreciation to all authors who have contributed to this special issue, the guest editors are pleased to present to the scientific community the final completed issue with 23 original research and review articles. For this team of guest editors our research careers began in the genomic era, which gave us the top prize: the Human Genome Reference Sequence. It will most certainly take many years for all of us to even begin realizing the real significance of this top prize. The genome era, however, also left us with a strong impression that “DNA determines everything.” The expression of a certain gene, for example, Gene C, is driven by the protein product of Gene B, while Gene B’s expression is driven by the protein product of Gene A. This is only a simple example of a gene expression regulation pathway, but eventually in every case, however more complex, we would end up at the end of the path, with a question that can no longer be answered this way. What then triggers the expression of the very first gene in the pathway? That initial event has to be executed by the business end of the genetic information flow, the proteins. This idea becomes easily very salient with the epithelium; that is, any environmental signal to the cells leading to however many genes being expressed must be transduced by the molecules, proteins, and their downstream products that are already present on the surface of the cells—the subject of our special issue: molecular landscaping for an interactive barrier in the epithelium.
The 23 papers published in this issue represented 7 of the 8 topics described in the Call for Papers, almost meeting our initial editorial goals. But more important, these excellent papers in more than one way fulfilled our wishes to help bring the scientific community’s focus on the molecular interactions at the environment-epithelium interface.
Karl Chai
Kenichiro Kitamura
Amanda McCann
Xue-Ru Wu