IL1B and neoplasm: On the other hand, FAP+ CAFs that are located distant away from PDAC cells stain weakly for α-SMA but instead express high levels of inflammatory cytokines including IL-6, IL-1, and LIF, and these are called inflammatory CAFs (iCAFs).59 It was proposed that myCAFs are possibly tumor restrictive, whereas iCAFs promotes tumor progression, partly explaining the observation that depletion of α-SMA+ CAFs accelerates PDAC progression in GEMMs.61 Importantly, these two phenotypes are interchangeable, based on spatial and biochemical niche of culture conditions.