CDYL2a and CDYL2b are the predominant isoforms expressed in human breast cancer cell lines and breast tumors. (A-B) qPCR analysis of the relative mRNA expression levels of four CDYL2 transcription variants in the indicated cell lines (A) and 60 primary breast tumor samples (20 samples for luminal, HER2-positive, and TNBC subtype, respectively). The relative expression levels of CDYL2a, CDYL2b, CDYL2c, and CDYL2d mRNA were first normalized to the GAPDH levels. Then, CDYL2a was used as a control in each breast cancer cell line (A) and breast tumor sample (B) as it was detectable in all samples. (C-D) qPCR analysis of the relative mRNA expression levels of CDYL2a (C) and CDYL2b (D) in 60 pairs of primary breast tumor tissues and matched normal breast tissues (20 samples for luminal, HER2-positive, and TNBC subtype, respectively). The expression levels of CDYL2a (C) or CDYL2b (D) in normal tissues were used as a control after normalization to the GAPDH levels. (E) Immunoblotting analysis of CDYL2 protein expression in the indicated cell lines with an anti-CDYL2 antibody. Vinculin was used as a loading control. (F) Immunoblotting analysis of CDYL2 protein expression in 14 pairs of primary breast tumor tissues and matched normal breast tissues with an anti-CDYL2 antibody. Vinculin was used as a loading control.