The initial screening of founder mice for the human CEACAM1 transgene was carried out by PCR analysis on mouse tail DNA. Briefly, tail samples (1-3 mm) were digested in 0.25 mL 0.4 N NaOH at 95uC for 10 to 15 min until tails were fully digested. Followed by adding 0.375 mL neutralization buffer (0.5 M Tris pH 8.0+20 mM EDTA). Digests were then diluted 10-fold. PCR were then performed by using Bio-Rad iCycler PCR (Bio-Rad Laboratory, Hercules, CA) with 2X fideliTaq PCR master mix (USB, Cleveland, Ohio). Two mL of diluted tail DNA was added into a final 20 mL volume reaction. The sense strand primer 59-CACCATGCCCAGCTAATTTT-39 and antisense strand primer 59-GTGGTCTGTTGCTCCCAGAT-39 only target the human CEACAM1 gene. The amplified product is 260 bp. The amplification parameters were initiated at 95uC for 5 min, then 95u C for 30 s, 53uC for 30 s, and 72uC for 30 s for 35 cycles, followed by 7 min at 72uC for the final extension. The primer sets for the mouse CEACAM1 gene are: sense 59-ATGAACAGTGAGG-CAGTCCC-39 and antisense 59-CAGAGGAAGAGTGTC-CAGGC-39. The amplification parameters were initiated at 95uC for 5 min, then 95u C for 30 s, 55uC for 30 s, and 72uC for 30 s for 35 cycles, followed by 7 min at 72uC for the final extension. The final product length is 155 bp.