SPINK1 and infection: In the proximal colon, EPM closed arm duration correlated with expression of three genes: serine protease inhibitor Kazal type 1 (Spink4), an inflammatory growth factor and tumorigenic marker, the secreted gel-forming mucin 2 (Muc2), which forms a mucus layer barrier on the colon wall, and regenerating family member 4 (Reg4), involved in infection and inflammation.