Based on limited published evidence, HNRNPA1L2 is involved in pre-mRNA packaging into hnRNP particles, nuclear export of poly(A) mRNA, and splicing regulation via spliceosome catalytic mechanisms. The protein binds mRNA 3'-UTR regions and modulates splice site selection. HNRNPA1L2 participates in chimeric RNA formation with adjacent genes 1 and functions as a trans-acting splicing factor whose activity can be modulated by histone variant H3.3-G34W mutations, with significant implications for RNA processing alterations in giant cell tumor of bone 2.