Essential for the generation of mature 18S rRNA, specifically necessary for cleavages at sites A0, 1 and 2 of the 47S precursor. Directly interacts with U3 snoRNA (By similarity). Interacts with NF-kappa-B p50/NFKB1 and NF-kappa-B p65/RELA. Ubiquitous. The mRNA 5'- and 3'-ends do not match to the genomic DNA. Truncated N-terminus. Extended N-terminus.