Due to travel restrictions caused by the COVID-19 pandemic, our first time-resolved SFX experiments at SACLA used a viscous extruder to deliver microcrystals of McCP-β, prior to photoexcitation, as previously described for time-resolved studies of NO binding to cytochrome P-450 NOR (Tosha et al., 2017 ▸). The gene discussed is CYP4F3; the disease is COVID-19.