Proteins involved in vitamin A signaling and retinoic acid metabolism including STRA6 (Berry et al., 2014, Szeto et al., 2001), RBP4 (Berry et al., 2014), and many intracellular lipid binding proteins (Levi et al., 2013, Manor et al., 2003) have been implicated in tumorigenesis of several cancers. Here, RBP4 is linked to cancer.