IL4 and breast cancer: To elucidate whether circWWC3-mediated IL-4 secretion affects macrophage alternative polarization in breast cancer microenvironment, THP-1 cells were co-cultured with breast cancer cells-conditioned medium, then qRT-PCR, western blot and ELISA were performed to detect the changes of M2 markers as well as chemokines (Figs. 2D and 3A).