We decided to focus on phospholipases D (PLDs), which catalyzes the hydrolysis of phosphatidylcholine (PC) into phosphatidic acid (PA), for three reasons: (1) PLD1 and PLD2 are two well-known targets of RalA and RalB (Jiang et al., 1995; Luo et al., 1998; Vitale et al., 2005), (2) PLD2 controls exosome secretion in breast cancer cells (Ghossoub et al., 2014), and (3) PLDs impact cancer progression (Bruntz et al., 2014). Here, RALA is linked to breast cancer.