The researchers, including Motoki Watanabe of Kyoto Prefectural University of Medicine and Shogen Boku of Kansai Medical University Hospital, examined polyphenols, such as chlorogenic acid, which is abundant in coffee. In the intestine, these compounds are broken down and converted into caffeic acid. The team then examined how this substance affects colorectal cancer cells at the molecular level. First, they confirmed that adding caffeic acid to colorectal cancer cells significantly suppressed the formation of "colonies" of cancer cells. They additionally found that caffeic acid binds to a protein called "RPS5," which is known to be associated with a poor outlook for recovery in colorectal cancer patients. Furthermore, they found that suppressing the expression of RPS5 -- the process by which gene information is turned into a function -- caused the cell cycle of cancer cells to halt at the preparatory stage before DNA replication.