PML and lymphoma: An important study by the Pandolfi group (6) examined PML expression in a wide array of human cancers and revealed a surprising discovery: while PML protein expression was reduced or absent in numerous cancers (prostate, colon, breast, lung, lymphomas, CNS, germ cell tumors), PML mRNA was expressed in all tumors, rarely mutated and was not subject to loss of heterozygosity.