HSPG2 and breast carcinoma: It is well-established that the PLC family, in particular PI-PLCs, mediates the signal transduction pathway by regulating several key membrane oncogenic receptor proteins, e.g., PLC-γ1 have roles in regulating EGFR activities [15], and PLC-δ4 is upregulated and enhances expression of HER2 and EGFR in MCF-7 breast cancer cells [16].