RBP1 and breast cancer: ARID4B was also found to associate with the mSIN3A HDAC complex [5], which is in turn known to be bound by the breast cancer associated tumor suppressor ING1 [20], [21], the well-characterized breast cancer metastasis suppressor BRMS1 [13], and the ARID family homolog ARID4A/RBP1 [22], which has also been identified as a breast cancer associated antigen [23].