IL4 and cancer: We further show that incubation of these same healthy myeloid cells in either cancer cell conditioned media or anti-inflammatory cytokines (IL-4 plus IL-13) induces a change in FRβ functionality from a nonbinding to folate-binding state, and that this activation of FRβ enables the receptor to bind and internalize folate-targeted drugs with high (~1 nM) affinity.