GPLD1 and breast cancer: This negative feedback mechanism between PARN and PLD2 was diminished in our breast cancer cell line, MCF-7, possibly due to an as-yet-unidentified regulator or pathway that leads to the attenuation of the large negative feedback of PARN on PLD2 expression, further supporting the significant role of PLD in this disease, as relates to the relative level of cell invasiveness and metastatic potential.