Activation of the BMP-Smad pathway by the GDF5-related factor BMP2 has been found to restore neurite growth in 1-methyl-4-phenylpyridinium (MPP+)-, 6-OHDA- and α-synuclein-induced in vitro models of PD (Goulding et al., 2019). Here, BMP2 is linked to Parkinson disease.