Serine/threonine kinase 35 (STK35) was originally identified as CLP36-interacting kinase 1 (Clik1) with autophosphorylation activity, exhibiting highest human tissue transcript levels in testes . The STK35L1 isoform contains a 133 amino acid N-terminal extension reported to interact with nuclear actin, and STK35L1 has been implicated in cycle progression maintenance and endothelial cell migration in human cell lines . We previously identified the STK35 mRNA as uniquely up-regulated in HeLa cells following transient hydrogen peroxide (H2O2) exposure, mediated through nuclear-localization of importin α2 and α4 proteins . Here, we report that human and mouse genomes encode an AS long non-coding (lnc) RNA in a 5’ head to head position that initiates within the second intron of Stk35. lncRNA levels rapidly increase (3-fold) in GC1 cells following 1 hr exposure to 1 mM H2O2, and then recover to original levels 8hrs after release from H2O2. siRNA knockdown of lncRNA does not impact transcript levels of Stk35 under normal and H2O2 stress conditions. Because STK35 is highly expressed in the testis, we performed Northern blot and in situ hybridization to identify its expression and cellular distribution in murine testis. Intriguingly, the lncRNA and Stk35 mRNA isoforms are expressed in different male germ cell types. These findings demonstrate that the Stk35 genomic locusincludes both coding and non-coding RNAs, with the latter implicated in early cellular stress responses. Our ongoing work will address the physiological significance of the lncRNA in mammalian spermatogenesis and cancer.