Interestingly, CD44 kd tumors showed nearly abolished CEACAM5 immunoreactivity in the paranecrotic areas (again, the area where CD44 was expressed in control tumors, see Fig. 3I) compared to control tumors (P < 0.0001, unpaired t‐test), but not at the tumor margin (P = 0.6, Fig. 4F). This evidence concerns the gene CD44 and neoplasm.