HPRT1 and cancer: MCF-10A expressed mainly LPAR6, BT-474 and T-47D expressed little amounts of LPAR1, MCF-7, SKBR3, and MDA-MB-468 expressed even smaller amounts of LPAR2, while MDA-MB-231 expressed a little of LPAR2 and LPAR6 compared to HPRT. All breast (cancer) cell lines responded to 1 μM LPA 18:1 with increasing cytosolic free calcium levels, too (Fig. 3c).