The surface protein levels of ABCG2 do not correlate well with mRNA levels in pancreatic cancer cells (Guo et al, 2009), suggesting that protein-regulatory mechanisms, such as post-transcriptional regulation, post-translational modifications, proteolysis, or sequestration in cell compartments, may affect the protein, without changing the transcript levels. This evidence concerns the gene ABCG2 and pancreatic neoplasm.