Whereas a number of studies have claimed that both CSF-1 and -2 drive M2 skewing of Mφ in mice with AKI (Zhang et al., 2012; Huen et al., 2015; Wang et al., 2015), it was controversially found that IL-34, another ligand for CSF-1R, does not polarize Mφ in murine AKI (Baek et al., 2015) and lupus model (Wada et al., 2019), indicating that CSF-1R signaling is dispensable in M2 Mφ polarization. Here, IL34 is linked to acute kidney injury.