SHH and amyotrophic lateral sclerosis: This has not been case in the field of ALS thus far, since common astrocyte differentiation protocols used for ALS modeling have usually relied on similar SHH and RA signaling conditions (e.g., Hall et al., 2017; Madill et al., 2017; Qian et al., 2017; Tyzack et al., 2017; Kelley et al., 2018b; Birger et al., 2019; Varcianna et al., 2019; Rajpurohit et al., 2020; Smethurst et al., 2020; Zhao et al., 2020).