FLT1 and systemic lupus erythematosus: Meanwhile we also find out that the level of PlGF is positively correlated with that of VEGF, ESR, and SLEDAI score in the SLE group, suggesting that PlGF is very likely to play its role in the angiopathy of SLE through enabling the secretion of VEGF and binding with it to activate VEGFR-1, and PlGF might also be relevant to the disease activities.