Despite this knowledge, tumor analyses of 9p21 often fail to adequately discriminate between alterations in INK4a versus ARF at the CDKN2A locus and frequently underestimate potential contributions of INK4b. This is especially true for less studied, rare tumors like sarcomas where many subtypes display 9p21 deletions but the relative importance of each gene to tumor pathogenesis remains poorly understood. The gene discussed is CDKN2B; the disease is sarcoma.