We have also previously demonstrated that PLC-β2 may counteract the expression of CD133 in invasive breast tumor derived cells cultured in normoxia [23] or hypoxia [21], allowing to hypothesize a role for this PLC isozyme in mediating the role of ATRA in DCIS-derived cells cultured under hypoxia. This evidence concerns the gene HSPG2 and ductal breast carcinoma in situ.