To investigate whether deficient degradation of phagocytosed material occurs in in vivo models of ALS-PFN1, dead neurons were stereotactically injected into the motor cortex of PFN1 C71G+/− knock-in and WT mice (Fig. 5), as microglia are known to phagocytose dead neuron material within the mammalian brain39. This evidence concerns the gene PFN1 and amyotrophic lateral sclerosis.