SP4 and AL amyloidosis: Previous studies showed that Sp4 is overexpressed in pancreatic, bladder, esophageal, breast, prostate, lung, colon, epidermal, thyroid, and rhabdomyosarcoma cancer cell lines and multiple myeloma cell lines, and KD of Sp4 significantly decreases cell growth and migration and induces apoptosis in nine cancer cell lines derived from six different tumors,[18, 19] suggesting that Sp4 is a pro‐oncogene.