MAPK8 and X-linked adrenoleukodystrophy: Thus, contrary to the common theory proposing that saturated VLCFAs promote pro-inflammatory responses by stimulating TLR signalling, our data provide evidence refuting that C26:0, the saturated VLCFA accumulating most prominently in X-ALD patients, directly activates TLRs but rather stimulates pro-inflammatory macrophage response through the JNK pathway.