Graphical representation of cell clusters based on co-expression of marker genes. (A) Z-Z plot of PRG4. (B) Spearman test for PRG4 high cells. CRTAC1 emerges. (C) Heat map of co-expressing CRTAC1 cells overlayed onto the PRG4 pattern showing high expression (Z > 1) of both genes in the superficial zone. (D) Overlay of cells with strong expressing (Z > 1) of three genes (CRTAC1, DPT, and ABI3BP) in PRG4 positive cells that show localization to the superficial zone.