VTCN1 and plasma cell myeloma: B7-H4 protein expression is limited in normal tissues, but aberrant B7-H4 expression is found in different solid tumor types, including breast [12], serious ovarian [13], colorectal [14] and pancreatic [15], lung [16], prostate [17], and renal cancer [18], as well as hematological malignancies including myeloma [19].