The present invention relates to SHIP inhibitor compounds and methods for using these compounds. In particular, the present invention discloses the following methods: (i) a method of treating graft versus host disease in a subject (ii) a method of inhibiting a SHIP1 protein in a cell (iii) a method of selectively inhibiting a SHIP1 protein in a cell (iv) a method for treating or preventing graft-versus-host disease (GVHD) in a recipient of an organ or tissue transplant (v) a method of modulating SHIP activity in a cell expressing SHIP1 or SHIP2 (vi) a method of treatment of transplants (vii) a method of inhibiting tumor growth and metastasis in a subject (viii) a method of treating a hematologic malignancy in a subject (ix) a method of inducing apoptosis of multiple myeloma cells (x) a method of treating multiple myeloma in a subject (xi) a method of inhibiting the proliferation of a human breast cancer cell and (xii) a method of treating breast cancer in a subject.