Fig. 1: GREB1 Is4 is expressed in melanoma cells.

A GREB1 mRNA expression in 17 cancer types was obtained from the TCGA database. The normal distribution across the dataset is visualized with box plots, showing the median and 25th and 75th percentiles. Points are displayed as outliers if they were above or below 1.5 times the interquartile range. The abbreviations used for all cancers are shown in https://gdc.cancer.gov/resources-tcga-users/tcga-code-tables/tcga-study-abbreviations. B GREB1 mRNA expression in normal skin (n = 556), primary sites (N = 102), or metastatic cutaneous melanoma (N = 367) from the GTEx and the TCGA datasets. The distribution of the data is visualized with violin plot. Black boxes span the first quartile to the third quartile; white lines in the black boxes indicate the median; the width of a violin plot indicates the kernel density of the expression values (***P < 0.001 by the Student’s t test). C Lysates from various cancer cells were probed with the indicated antibodies. Full or Is4 refer to full-length GREB1 or GREB1 Is4, respectively. GREB1 and GREB1 Is4 protein structure and antibody recognition sites were illustrated. Specificity of anti-GREB1antibodies (#1) and (#2) was checked in Supplementary Fig. S1B. HSP90 was used as a loading control. D Melanoma-specific GREB1 Is4 mRNA transcription in various cancer cells was examined by qPCR using region-specific primers. The amplified regions are depicted in Supplementary Fig. S1D. The data are presented as the fold-change relative to the GREB1 mRNA levels detected in MCF7 cells. E Transcribed regions and open chromatin loci of the GREB1 gene locus in PDX established from four melanoma tissues from three patients were plotted. PDX1 and 2 were established from the same patient. The peak levels of human GREB1 mRNA transcription and chromatin accessibility were obtained from the RNA- and ATAC-seq data, respectively. The RNA-seq data of A375 cells derived from GEO datasets (GSM1138787) was plotted as a negative control. The closed triangles or red box show exon 1 and 19 or putative GREB1 Is4 promoter, respectively. Exon numbers were assigned based on the GREB1 transcription ID: ENST00000381486.7 (GREB1-204). F Colo679 and MCF7 cells were stained with anti-GREB1 (#2) or anti-GAPDH antibody and counterstained with Hoechst33342. GAPDH or Hoechst33342 was used as cytosolic or nuclear marker, respectively. Scale bars in F, 20 μm.