E18.5 mTurq2-Col4a1 mouse backskin shows correct and robust expression of mTurq2-COL4A1 in the dermal – epidermal junction basement membrane. (A) Average intensity projection of backskin from WT E18.5 embryo labeled with Hoechst (merge, top), anti-laminin β-1 antibody (A’), and anti-collagen IV antibody (A’’). No signal was observed in the mTurq2 channel (A’’’). (B) As in A, except backskin from a mTurq2-Col4a1/+ embryo. Robust mTurquoise2 signal recapitulates the labeling pattern of the collagen IV antibody. (C) Pearson’s correlation coefficient (r) measuring the correlation between laminin β-1 and collagen IV expression (antibody labeling) in WT and mTurq2-Col4a1/+ E18.5 backskins as labeled. Larger datapoints—biological replicates (n = 3 embryos), smaller datapoints—individual images per replicate (n = 10 per embryo). (D) Average intensity projection of backskin from WT E18.5 embryo labeled with Hoechst (merge, top), anti-laminin β-1 antibody (D’), and anti-perlecan antibody (D’’). (E) As in D, except backskin from a mTurq2-Col4a1/+ embryo. (F) As in C, except measuring the correlation between laminin β-1 and perlecan. Scale bar, 20 µm. ns = not significant, Mann–Whitney U test.