MAP3K1 and proximal spinal muscular atrophy: As concerns SMA, it is likely that the decrease in SMN level leads to cellular stress, resulting in JNK pathway phosphorylation and contributing to MN death, as proposed by Genabai et al. (2015): they reported the activation of the MAP3K proteins ASK1 and MEKK1 in the spinal cord of SMA patients and mice, suggesting that at least two possible signaling pathways can be involved in JNK activation.