Subsequent investigation supported this hypothesis as follows: (a) MEL (4 or 6 μg/mL) inhibited the expression of ERK1/2, ERK5, JNK and MEK5 at the mRNA level in BC cells, as analysed using qRT‐PCR; and (b) MEL (4 or 6 μg/mL) constrained the expression of ERK5, MEK5, JNK and ERK1/2 at the protein level, as well as that of p‐ERK1/2, p‐JNK and p‐38 at the phosphorylation level. Here, MAP2K5 is linked to breast cancer.