The N-terminal LXCXE motif of the LT protein has been shown to interact with known oncogene Rb and is conserved in other cancer-causing viruses. Studies suggest that LT may also preserve cell proliferation signals such as c-Myc and cyclin E and cause DNA injury to the p53 tumor suppressor.Meanwhile, sT has been shown to induce cell proliferation through hyper-phosphorylation of the translation initiator 4EBP1 as well as inhibition of a ubiquitin ligase complex responsible for degradation of cellular proliferation signals. sT also contains a region known as the LT stabilization domain (LSD), which potentiates the LT proteins oncogenic function. Unlike LT, MCC samples have been identified that express sT alone, and sT expression in fibroblasts has been shown to cause MCC phenotype development. UV light
About 20% of MCC tumors are MCV negative. In contrast to MCV-induced MCC, these tumors tend to have much higher mutational burdens with mutational signatures characteristic of UV damage. Genes frequently mutated in MCV-negative MCC include p53 and Rb, among others. The link between MCC and UV exposure has been demonstrated through various epidemiological studies indicating a higher incidence of MCC in fair-skinned people in areas of high UV exposure, as well as among those receiving UV phototherapy. The typical distribution of MCC in sun-exposed regions and its co-occurrence with other skin cancers also indicate that UV exposure is a contributing factor to MCC development. It is unclear whether this is through direct mutational impact, immune down-regulation, or some combination of the two.
To perform the test, the examiner grasps and ulnar deviates the hand when the person has their thumb held within their fist. If sharp pain occurs along the distal radius (top of forearm, about an inch below the wrist), de Quervains syndrome is likely. While a positive Finkelsteins test is often considered pathognomonic for de Quervain syndrome, the maneuver can also cause pain in those with osteoarthritis at the base of the thumb. Differential diagnosis
Differential diagnoses include:

Osteoarthritis of the trapezio-metacarpal joint
Intersection syndrome—pain will be more towards the middle of the back of the forearm and about 2–3 inches below the wrist, usually with associated crepitus. Wartenbergs syndrome: The primary symptom is paresthesia (numbness/tingling). Treatment
As with many musculoskeletal conditions, the management of de Quervains disease is determined more by convention than scientific data. A systematic review and meta-analysis published in 2013 found that corticosteroid injection seems to be an effective form of conservative management of de Quervains syndrome in approximately 50% of patients, although more research is needed regarding the extent of any clinical benefits. Efficacy data are relatively sparse and it is not clear whether benefits affect the overall natural history of the illness. One of the most common causes of corticosteroid injection failure are subcompartments of the extensor pollicis brevis tendon.Most tendinoses are self-limiting and the same is likely to be true of de Quervains although further study is needed.Palliative treatments include a splint that immobilized the wrist and the thumb to the interphalangeal joint and anti-inflammatory medication or acetaminophen.