Summarized schematic of XEN-to-iPS and ES-to-iXEN lineage conversions. (Left) Hypothesized reprogramming route taken by XEN cells. Sizes and number of arrows reflect the likelihood of cells progressing from one state to the next (smaller/single arrows: few cells progress; larger/more arrows: many cells progress). Reprogramming XEN cells initiate expression of Oct4-GFP, then downregulate PDGFRalpha. This downregulation step represents a bottleneck during reprogramming since few Oct4-GFP+ cells progress to this state. Following PDGFRalpha downregulation, a large proportion of cells upregulate SSEA-1. (Right) Hypothesized lineage conversion of ES-to-iXEN cells. Initial upregulation of both, PDGFRalpha and Gata6-Venus, is followed by downregulation of SSEA-1. No obvious bottlenecks are detected during ES-to-iXEN conversion.
