STAT3 and AL amyloidosis: Furthermore, using IHC method, the cell proliferation markers Ki-67, PCNA and the key protein of STAT3 pathway p-STAT3 was significantly decreased, the apoptosis related gene cleaved Caspase 3 and PARP were significantly increased by GLA (Fig. 6F), further suggesting that GLA inhibited the cell proliferation in multiple myeloma through STAT3 pathway.