PFN1 and amyotrophic lateral sclerosis: Also, loss of function mutations in PFN1 (profilin 1) have been identified in familial ALS (Wu et al., 2012a) and profilin has been shown to be essential in regulating actin dynamics necessary for phagocytosis, phagosome formation and is upregulated in microglia following insult (Pearson et al., 2003; Dong et al., 2004; Kim et al., 2012).