Re: "End this Stem Cell Racket" ¹ and "Working with Stem Cells? Pay Up" ² : The novelty of claim one in Thompson's (WARF) patent is not in parts (i) through (iii), but in the final clause: "is inhibited from differentiation when cultured on a fibroblast feeder layer." Is it not possible to inhibit from differentiation using other techniques than a fibroblast feeder layer (e.g., see US Patent No. 6,800,480)? New approaches such as this one have been addressed not only because of Thompson's '806 patent, but because of the presence of impurities (such as viruses) in the feeder cells. If the non-feeder cell techniques do not work and using a fibroblast feeder layer is truly novel, then the patent is probably worth its reputed $400,000 license.