TNF and leukemia: While TNFα has been implicated in the remodeling of blood vessels and shown to promote angiogenesis during inflammation [44, 45], to our knowledge the TNFα-induced switch from Sca-1high ECs to Sca-1low ECs, and in turn from an arteriole- to a sinusoid-enriched BM niche as observed during leukemia growth has not been previously reported.