An alternative possibility, which may be provocative, is that upregulation of serum U6 levels is a preamble to cancer initiation or suggestive of a pre-cancerous state, similar to the creation of a niche for metastasis by the vascular endothelial growth factor receptor-1-positive (VEGFR-1+) hematopoietic bone marrow progenitor cells before the arrival of cancer cells [33]. Here, FLT1 is linked to cancer.