The evidence that Fibro-BKO cells always displayed a pattern of markers expression suggestive of lower gastrointestinal tract differentiation (CK7−/CK20+/CDX2+) and the confirmation that the phenotypical pattern of the MCF-PKO cells was consistently suggestive of upper gastrointestinal tract differentiation (CK7+/CK20−/CDX2−)35 prompt us to speculate that if metastases are secondary to circulating factors rather than circulating cells, the target cells that uptake the onco-information and turn malignant would vary depending on the type of the cancer that releases the oncofactors. The gene discussed is KRT7; the disease is cancer.