FABP4 and ductal breast carcinoma in situ: FABP4 is mainly expressed in adipocytes and macrophages and can act as a functional marker of tumour-associated macrophages in primary tumours, and is a key molecular sensor regulating the differentiation and function of primary tumour macrophages, leading to the progression of ductal carcinoma in situ (DCIS) of the breast to progression of invasive disease [7].