POLH and B-cell non-Hodgkin lymphoma: Notably, the exposure of Sig.F3, which resembles the previously reported signature G7 that correlates with the activity of POLH and the rate of somatic hypermutation (SHM) in IGHV regions in B cell lymphomas,40,41 was significantly elevated in C1 and C2 tumors compared with C3, with C1 also showing the greatest exposure.