 In humans, experimental evidence for alternative splicing exists; alternative transcription initiation and the cleavage sites of the mitochondrial and nuclear transit peptides need to be experimentally verified.Knockout mice of GPX4 die at embryonic day 8
and conditional inducible deletion in adult mice (neurons) results in degeneration and death in less than a month.Targeted disruption of the mitochondrial GPx4 isoform (mGPx4) caused infertility in male mice and disruption of the nuclear GPx4 isoform (nGPx4) reduced the structural stability of sperm chromatin, yet both knockout mouse models (for mGPx4 and nGPx4) were fully viable.