Paraffin sections of xenograft outgrowths of CEACAM1-4L and mutants in MCF7 cells grown in humanized mammary fat pads were stained with hematoxylin and eosin (H&E). Stable MCF7 cell clones transfected with vector control (A), CEACAM1-4L wild type (D), T457D (G), T457A (J), S461D (M), S461A (P), T457D+S461D (S), and T457A+S461A (V) are shown. Immunostaining was performed with anti-CEACAM1 antibody 5F4 for stable MCF7 cell clones transfected with vector control (B), CEACAM1-4L wild type (E), T457D (H), T457A (K), S461D (N), S461A (Q), T457D+S461D (T), and T457A+S461A (W). Immunostaining with M30 antibody was performed for stable MCF7 cell clones transfected with vector control (C), CEACAM1-4L wild type (F), T457D (I), T457A (L), S461D (O), S461A (R), T457D+S461D (U), and T457A+S461A (X). (Magnification 400×)