SFRP4 and adenomyosis: We found a high expression of IGFBP5 in both nerve fibers labeled by neurogenic proteins and surrounding SFRP4+ NKT cells in tissue slides from the adenomyosis pain group, which indicates that the IGFBP5 that induces the differentiation of stem cell clusters into neurogenic cells might be derived from SFRP4+ NKT cells.