ABCG2 and acute myeloid leukemia: ,40 Clinically, high levels of ABCG2 expression have been observed in various solid tumors, particularly in adenocarcinomas of the digestive tract, endometrium, lung, and breast, and melanoma.41, 42, 43 Furthermore, researchers found44 that ABCG2 was overexpressed in 33% of patients with acute myeloid leukemia, and this overexpression was significantly linked to shorter disease-free survival and an increased risk of relapse.45, 46, 47