In keeping with this notion, the previously reported expression of K15 mRNA in many KS biopsies from AIDS patients [70], as well as the presence of activating epigenetic marks on the K15 genomic locus [91], we show here that K15 is spontaneously expressed in KSHV-infected blood vascular (HuARLT2) and lymphatic endothelial cells (Figs 2E and 7–9), as well as in a substantial proportion of KS spindle cells in tumor biopsies (Fig 10). This evidence concerns the gene KRT15 and neoplasm.