To further confirm the KAT6A acetylation of SMAD3, we generated two rabbit polyclonal antibodies that specifically recognized SMAD3‐K20ac or SMAD3‐K117ac through a commercial vendor and validated their specificity in a clinical breast cancer specimen and MDA‐MB‐231 cells (Figure S2B–D, Supporting Information). This evidence concerns the gene SMAD3 and breast cancer.