Some large subunit ribosomal proteins, such as RPL5, RPL9, RPL10, RPL11, RPL15, RPL21, RPL22, RPL23A, RPL27, RPL31 RPL34, RPL35, RPL36, and large subunit ribosomal proteins, such as RPS7, RPS15, RPS15A, RPS17, RPS19, RPS20, RPS24, RPS27, and RPSA, are reported to have significant roles in the progression of various types of cancers including lung, colon, breast, and pancreatic cancers (60–62). Here, RPL21 is linked to cancer.