PBX1 and systemic lupus erythematosus: Early research has identified the transcription factor PBX1 as a lupus susceptibility gene located in the classical 1q23 susceptible loci of humans[19] and mouse homologous sle1a sites.[20] Shen et al[14] showed that PBX1 was specifically downregulated in autoimmune B-cells and negatively correlated with disease activity as a therapeutic target in SLE.