This is an Expression of Concern regarding: Russell M.L. Simpson, Xuechong Hong, Mei Mei Wong, Eirini Karamariti, Shirin Issa Bhaloo, Derek Warren, Wei Kong, Yanhua Hu, Qingbo Xu, Hyaluronan Is Crucial for Stem Cell Differentiation into Smooth Muscle Lineage, Stem Cells, Volume 34, Issue 5, May 2016, Pages 1225–1238, https://doi.org/10.1002/stem.2328