FAP and breast cancer: In vivo studies using the breast cancer 4T1 model depleted FAP CAFs by DNA vaccines led to increased expression of IL-2 and IL-7 (inducing Th1 cell differentiation) and decreased expression of IL-4 and IL-6 (inducing Th2 cell differentiation) in tumor homogenates, indicating that CAFs regulate the transition from Th1 to Th2 mediated immunity (Liao et al., 2009).