Heterozygote (GA) individuals for rs4148382 had a significantly higher MRP1 protein level than wild type (GG) individuals in COPD patients (p = 0.026) (Figure 4a) and in the control group minor allele carriers (GA/AA) for rs4148382 had a significantly higher MRP1 protein level than wild type (GG) individuals (p = 0.037) (Figure 4b). Here, ABCC1 is linked to chronic obstructive pulmonary disease.