Furthermore, cultures of RA neutrophils with or without added perforin viewed after 18 h at 37 °C contained a mixture of viable cells and cells at various stages of programmed cell death via apoptosis, pyroptosis, or NETosis, but with no discernible differences in ratios of death pathways between samples containing only endogenous perforin pores or those with added perforin. This evidence concerns the gene PRF1 and rheumatoid arthritis.