Transcriptional activator involved in cold stress response (PubMed:14675437, PubMed:20807373, PubMed:22246661). Regulates positively the expression of genes involved in reactive oxygen species (ROS) scavenging such as peroxidase and superoxide dismutase during cold stress. Transactivates a complex gene network that have major effects on stress tolerance and panicle development (PubMed:20807373). By cold stress. Arabidopsis plants overexpressing MYB4 show dwarf phenotype and increased tolerance to cold and freezing (PubMed:14675437). Barley plants overexpressing MYB4 show a slight retarded growth and increased tolerance to cold and freezing (PubMed:22246661).