We hypothesized that rhythmicity of PER2 would diminish in amplitude along a continuum from mouse small intestinal explants, intestinal organoids, a nontransformed mouse small intestinal epithelial (MSIE) cell line (Whitehead et al., 1993) and transformed human colorectal adenocarcinoma cells (Caco-2). The gene discussed is PER2; the disease is colorectal adenocarcinoma.