ESR1 and breast cancer: To further confirm the association of DSCAM-AS1 expression with ERα, we analyzed ERα and DSCAM-AS1 RNAs in a panel of breast cancer cells by qRT-PCR, confirming that DSCAM-AS1 is confined to cells expressing ERα, with the exception of cells with HER2 amplification (SK-BR-3), as already noticed in previous in silico analysis (Supplemental Figure 3C).