a, Immunofluorescence analysis of E-CADHERIN (green), mCHERRY (magenta) and DAPI nuclear staining (blue) at the morula stage in control embryos and in embryos electroporated with mCherry-TRIM21 mRNA and mouse anti-aPKC antibody (n = 10). b, Immunofluorescence analysis of anti-mouse secondary antibody to detect the electroporated aPKC antibody (green), E-CADHERIN (red), rabbit anti-aPKC to detect the aPKC protein (magenta) and DAPI nuclear staining (blue) in at the morula stage in embryos either electroporated with mCherry-TRIM21 mRNA only or with mCherry-TRIM21 mRNA and mouse anti-aPKC antibody. c, Quantification of aPKC cortical intensity (based on rabbit anti-aPKC signal) in outer cells at the morula stage in embryos electroporated either with mCherry-TRIM21 mRNA only or with mCherry-TRIM21 mRNA and mouse anti-aPKC antibody (n = 270 cells from 30 embryos). d, Immunofluorescence analysis of SOX2 (green), rabbit anti-aPKC to detect the aPKC protein (red), anti-mouse secondary antibody to detect the electroporated aPKC antibody (magenta) and DAPI nuclear staining (blue) at the morula stage in embryos electroporated either with mCherry-TRIM21 mRNA only or with mCherry-TRIM21 mRNA and mouse anti-aPKC antibody. Yellow arrowheads point to outer cells expressing SOX2 in a mouse morula stage embryo. 2 independent experiments. e, Quantification of SOX2 fluorescence intensity, normalized to DAPI intensity, in outer cells at the morula stage in embryos electroporated either with mCherry-TRIM21 mRNA only or with mCherry-TRIM21 mRNA and mouse anti-aPKC antibody (n = 120 cells 18 embryos). t-test, *p < 0.05. f, Immunofluorescence analysis of TEAD4 (green), anti-mouse secondary antibody to detect the electroporated aPKC antibody (magenta) and DAPI nuclear staining (blue) at the morula stage in embryos electroporated either with mCherry-TRIM21 mRNA only or with mCherry-TRIM21 mRNA and mouse anti-aPKC antibody. 2 independent experiments. g, Quantification of TEAD4 fluorescence intensity, normalized to DAPI intensity, in outer cells at the morula stage in embryos electroporated either with mCherry-TRIM21 mRNA only or with mCherry-TRIM21 mRNA and mouse anti-aPKC antibody (n = 90 cells from 10 embryos). t-test, ns = not significant. Scale bars as displayed in figures.