STAT4 and bronchopulmonary dysplasia: Relevant studies have shown that in the BPD lung tissue of newborn mice, with the increase of DNA methylation, the expression level of signal transducer and activators of transcription factor 4 (STAT4) is significantly lower than that in the control group, indicates that STAT4 may be regulated by DNA methylation in the occurrence and development of BPD (34).