KRT72 (keratin 72) is an intermediate filament protein with dual roles in hair follicle structure and innate immunity. In its canonical function, KRT72 is a component of keratin filaments specifically localized to the inner root sheath (IRS) of hair follicles, where it contributes to hair formation and follicle architecture 1. Beyond its structural role, KRT72 functions as a host antiviral restriction factor against HIV-1 infection. The protein restricts HIV-1 replication in resting CD4+ T cells by sequestering incoming HIV-1 capsids within cytoplasmic intermediate filaments, thereby inhibiting their nuclear trafficking and preventing integration of viral DNA 2. This antiviral mechanism is clinically significant as pathogenic SIV lineages (SIVrcm/mnd-2) have evolved the accessory protein Vpx specifically to target KRT72 for degradation, circumventing this restriction barrier 2. Recent evidence indicates KRT72 contributes to HIV-1 latency establishment in cellular reservoirs, positioning it among novel host factors influencing viral persistence 3. Additionally, genetic variation affecting KRT72 expression modulates cellular chemotherapy sensitivity; reduced KRT72 expression associated with certain SNPs correlates with improved cyclophosphamide sensitivity but paradoxically with poor progression-free survival in breast cancer patients 4. These findings establish KRT72 as a multifunctional protein bridging structural biology with antiviral and oncological relevance.