ALDH7A1 and breast cancer: To further confirm the involvement of cAMP in β-adrenoceptor-mediated LD expansion in breast cancer cells, experiments were carried out in the presence of IBMX (10–30 μM), a non-selective phosphodiesterase (PDE) inhibitor, in order to establish whether the inhibition of PDEs can potentiate β-adrenoceptor-mediated LD expansion in MCF-7 breast cancer cells.