For example, ABCG2 gene is responsible for the active secretion of clinically and toxicologically relevant substrates into the milk and soluble CD14 in colostrum and milk acts as a sentinel molecule and an immune modulator, which provide innate responses against bacterial infections in the calf (Olsen et al., 2007; Ibeagha-Awemu et al., 2008). Here, ABCG2 is linked to bacterial infectious disease.